What form is the compensation reported on ?

I cannot find that TAM anywhere. 

It's apparently supposed to be treated the same as worker comp. It also seems Chicago isn't issuing their W2 correctly for years.

I see where it is being entered as Other Income on Schedule 1:

For description enter "per TR 32-153-91" Enter the amount of the income with a minus sign (-) in front of it.

That's per Intuit, for TurboTax, by the way.

I answered the same question here, four years ago. Except I should have written "I'm guessing that its public-safety workers are NOT covered by Social Security,"

 https://accountants.intuit.com/community/proseries-tax-discussions/discussion/excludable-compensatio... 

In any case, the only taxpayer who can rely on a Technical Advice Memorandum is the one who asked for it.  It doesn't appear that you even have the correct reference number for it, so good luck.