Well normally you cannot file I-485 with USCIS while in removal proceedings, which includes having a final order. The reason for this is that in most cases being placed into removal proceedings moves the jurisdiction over I-485 from USCIS to the Immigration Judge.

There is one exception to the above rule and that's for "arriving aliens" which is a fancy way of saying Parolee, where even if placed into removal proceedings USCIS still maintains jurisdiction over your case. Basically a bunch of court decisions from back in the day when conflicting regulations caused nobody to have authority over I-485 of arriving aliens.

So yes, your lawyer is right, you can file for AOS now and deal with the removal order after your green card is approved. The main argument will either be missing notice and bashing the former lawyer, or/and request for sua sponte reopening and termination since being a permanent resident and having a removal order puts you in a very strange position where you are ordered removed for reasons which are no longer valid.