The AMA is a well-established organisation, going back at least 4 decades. I have not paid attention to it in the last 15 years, so everything here is out of date.
It performs several functions, including organising the highest levels of American motorcycle racing. It also lobbies, but there is a history (again, I have not been paying attention) of the AMA going one way while its membership goes another. It really can't do anything about helmet laws, for example, because there is no consensus among its membership.
If they advertise a service, they provide it. I am sure that they sub-contract roadside asistance to local towing companies, just like the AAA does in outlying regions. If the price is right, go for it.
The AMA operates a service called "Mowtow".
It's a 24-hr a day service to pick up you and your bike (or scooter) and deliver you to a dealer.
For 25 bucks a year (AMA member), you get an ID number and a toll free contact number.
There are some restrictions, such as having to be farther than 2 miles from your home, and possibly some some distance restrictions,
See www.amadirectlink.com . Ask them about any concerns you have.
Personally, I believe it's worthwhile to belong to the AMA.
They organize / sponsor a lot of touring related activities, and they have a pretty good package of discounts for members (KOA, motels, rental cars, etc).
I have, for some time, used "TheAutoClub" as my motorcycle road service provider. I use the Advantage plan, which provides unlimited towing charge coverage, plus many other benefits. It also covers any motorcycle you are riding, not just the "named" vehicle.