I can't imagine they would pull it for performing better than other drives. That would be too risky, IMO. It would also not offer any good return to the company. I think that one should be left to the tin foil hat wearers

.
Look at it like this:
1. Person buys SSD from Company, expecting TRIM, a stated feature supported, to work, which gives good steady-state performance.
2. Person finds TRIM is not working.
3. Company fixes it, once they verify the new firmware works well enough. It now works as it was originally advertised.
4. Company finds that these older drives now perform as well or better than their newer ones, and pull the update, because the new one needs to look better.
5. Person finds small shred of evidence that this was done due to the improved performance. Company has now reneged, and has broken a fixed part, effectively.
6. Person finds lawyer, and other persons. Lawyer makes money. Company gets a lot of hassle. Person and persons get crap in the end, but the satisfaction of having annoyed Company's management.
I wonder if there were compatibility issues that took awhile to start being noticed? I could definitely see the CS people at some of these companies having no more of a clue about something as generally esoteric as a firmware download going missing, and thus there being a lot of silence from them.