Thanks for your input, everyone. An AC supervisor called me yesterday and resolved the situation satisfactorily. She was a great representative for customer service and of the airline itself.

I'm on an AC flight almost once a week and have cancelled/rescheduled returns but never outbounds. My main concern with this situation is that the policy for cancelling the outbound is quite different than cancelling a return. And even as someone who flies the airline a lot, I was not familiar with the restrictive policy and it doesn't seem to be readily accessible in writing and is definitely not on the booking confirmation document.

I hope the situation doesn't come up again, but I'm probably just going to book one-ways from now on. Even if the tax situation comes into play