I just received a reply to my Chase SM (A week later) asking them to match the offer:

Thank you for contacting Chase about your United
MileagePlus credit card account and enrollment bonus.

We are pleased to confirm we have received your request to
exchange the offers on the account. Please reply to this
message with the name of the person you would like to add
to the account. Once the Authorized User is added, a
credit card with the new user's name will be mailed to the
address listed on your account and 5,000 bonus miles will
be added to your account. In addition, you can earn 10,000
bonus miles if you spend $25,000 in purchases in any
calendar year (January through December). Once all of the
above have been met you will have received a total of
65,000 miles.

We are pleased to inform you that we have honored your
request and issued a $50.00 statement credit. The credit
will be reflected on your next billing statement.

If you have any further questions, please reply using the
Secure Message Center.

My first billing statement is 3 weeks away and I already have the $50 credit on the account.