If the story is exactly as you adivse- this is pretty ridiculous- A colleague of mine lost a paper ticket about a year ago flying from ZRH to YUL to STL (code share from ZRH to YUL on Swiss)- at YUL they issued him a "crayon ticket" which enabled him to travel onwards at no additional cost. I could not find anything specific to AC, but DL spells out there policy quite well:

Lost Tickets
What you need to know before applying for a refund

If your paper ticket has been lost, stolen, or damaged, you can complete a Lost Ticket Application, available at our ticket counters, ticket offices, or your travel agency. You have the option to continue your travel even if your ticket is lost. If you find your lost ticket, you can return the ticket to us to avoid additional charges in some cases.

Requirements and Restrictions
You should note the following requirements and restrictions when applying for a lost ticket refund:
The Lost Ticket Application must be submitted within 13 months of the day you purchased the lost ticket
The application may take 90 days to process
A $100 non-refundable processing fee will be charged for each lost ticket
You must provide the ticket number in order to process a refund
Refunds
Generally, a refund will be provided in the same form of payment by which you purchased the original ticket. For cash or check purchases, a check will be issued after your application has been processed.
If you paid by credit card and return the ticket to us, you will see the refund credit on one of your next two credit card statements
You will receive no other notification except for the refund credit on your credit card statement
If the refund credit does not occur, please contact your credit card company directly
How to Determine the Lost Ticket Number
The lost ticket number (a 13-digit number beginning with "006") must be identified before a refund can be processed.

Method of Payment Ticket Number Location
Credit Card On your copy of the signed charge form or billing statement.
Cash Contact the original ticketing location and provide them with the exact date of purchase for the ticket.
Check On your canceled check.
Travel Agent Contact the agency for your ticket number.


If you are a travel agent submitting an application on behalf of your customer, please enclose a copy of the agent's lost ticket coupon.

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Lost Ticket and Plans to Continue Travel

Unused Ticket
If your unused paper ticket is lost and you still plan to travel with Delta, a new ticket can be purchased at the original fare. If the original fare cannot be determined, a new ticket must be purchased at the applicable fare at that time. In most cases, the original ticket will be refunded less a $100 processing fee for each ticket.

Partially Used Ticket
If your partially used paper ticket is lost during travel and you still plan to continue travel, a replacement ticket will be issued for the lost ticket and a $100 processing fee will be applied.

Lost Ticket and No Plans to Continue Travel
If you have lost your paper ticket and no longer plan to travel, a refund can be issued less a $100 processing fee for refundable tickets. Remember that non-refundable tickets will not be refunded when the passenger is not continuing travel.

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Returning Found Tickets
If the original lost ticket coupons are found and returned to Delta prior to continuation of travel on a replacement ticket, the $100 processing fee will be waived. Please return:
the original remaining coupons
a copy of the new ticket (if you plan to continue travel)

a copy of the Lost Ticket Application
Via U.S. Postal Service:
Delta Air Lines, Inc.
Post Office Box 20537
Atlanta, GA 30320-2537
Via Courier Service:
Delta Air Lines, Inc.
Passenger Refunds, Dept. 654
700 South Central Avenue
Hapeville, GA 30354

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I would write to the AC refunds office at:
Refund Services


Many tickets are non-refundable, while others may have penalties, which limit their refundable value. In most cases, the words “non-refundable” or “non-ref” are clearly printed on the ticket and ticket receipt, above the passenger name.

How long is my ticket valid for?

The majority of tickets are valid for one year from date of original issue. Please verify the validity of your ticket with your travel agent or at an Air Canada ticket office.

Can I give my ticket to someone else?

Tickets are non-transferrable and can only be used by the person whose name appears on the ticket.

Can I obtain a refund for my ticket?

To determine if any portion of your ticket may be refunded, please bring it to the original issuing office. The ticketing specialists at your travel agency or at an Air Canada ticket office are best equipped to examine your ticket and provide you with any ticket information or details you may require.

Or you may forward your request and any original unused Air Canada ticket to:

Air Canada Refund Services,
P.O. Box 6475,
Winnipeg , Manitoba,
Canada
R3C 3V2

For information on the status of a refund, please call (204) 941-2851, fax (204) 941-2789 or write to [email protected]. Please be sure to include your ticket number and mailing address with your request.

Good luck on helping him with the refund!