What rule book does chess.com use?

Please take a look at this position from a bullet game I just played.

I was Black, and White had just run out of time. The game was drawn due to "insufficient material," and I know what that is. I've had hundreds of games get drawn due to insufficient material, so I don't need any people explaining what it means.

My problem is that under the FIDE Laws of Chess, a game is drawn if a player runs out of time if "the position is such that the opponent cannot checkmate the player's king by any series of legal moves." This is not the case in this position. It is legal for White to allow Black to capture both rooks and one pawn and for the other pawn to promote to a knight. Then, both white pieces can be moved to the corner for Black's bishop to deliver checkmate. I played through some legal moves in an analysis board and confirmed that this is possible. I understand that it is extraordinarily unlikely for White to ever allow this in an actual game, but that does not matter, for the FIDE rules merely specify "any possible series of legal moves."

So chess.com doesn't use FIDE rules. That's fine as long as it is clear what set of rules it abides by. Is the rule for this situation simply that if the opponent of the player who only runs out of time has just a king and a bishop or knight, the game is drawn, regardless of what pieces the player has? Why doesn't chess.com just use FIDE's rules anyway?

I've read in other threads that the FIDE rule would be too hard to program.  Chess.com uses USCF, but I think slightly modified to never allow "helpmates".  There have been dozens of threads on this and I'm no expert, so I'll try to pull a few up for you...

Yeah, there are 35 pages of previous threads.  Bound to be a few worth reading.

https://www.chess.com/forum/search?keyword=insufficient%20material

I see. Thanks for the helpful response!

Happy to help....