Draw on time by insufficient material

My opponent just flagged in a drawn position in live chess and was awarded a draw by insufficient material.  Is this just a practical consideration, or an oversight?  There was a legal sequence of moves available leading to checkmate.  I think it requires underpromoting to a bishop which just happens to be the right colour for a helpmate.  It's not really a big deal, since I was about to offer a draw anyway for obvious reasons, but technically if black flags in this position I'm pretty sure a white win is the correct result.  

Chess.com use USCF rules, not FIDE. I'm waiting for the day a GM gets caught out by this in a Titled Tuesday event... 

i had a similar occurrence myself a few years ago, i started a topic on it then. Unfortunately, v3 means it's a long and laborious task to find it...

Ah, I take it USCF rules are different then.  Shame because the FIDE rules on this seem pretty good and clear.  It makes perfect sense to me that if you run out of time you should be assumed to make the worst possible moves but not suffer any worse than this.  It seems clear, fair, and unambiguous, and nobody has to make a judgement about how stupid they think you are.  It would seem quite complicated to have rules different to this as you'd have to enshrine in the rules somewhere what counts as stupid moves.  For example, what if the position had been thus:  

In a time scramble you can easily see someone, having pushed the pawn to the 7th rank, promoting it and losing, but if their flag falls as they're trying to promote then they get an automatic draw? 

I thought USCF used to involve complications involving an arbiter and a delay clock, which they obviously can't do online.  Even then, I guess I sort of assumed this was just considered a practical fudge similar to quickplay finish rules where you can sometimes claim draws.  I didn't realise they had different rules for if your flag actually fell!  

Yeah, this version of the site still has some serious problems with navigation and finding stuff.  The other day I tried to look up the rules for the daily chess, which used to be incredibly easy to find, (impossible to miss, actually, because they wanted to make sure people weren't using computers!)regarding books, databases, engines, etc.  because I wanted to show that chess.com had clear rules regarding stuff like that, but now it seems they don't exist anywhere, except a cursory note in some unrelated place that you really have to go looking for, and they aren't at all comprehensive.  You'd really think they'd make the rules they're using pretty obvious and easy to find, especially if they're not using the normal rules!  

 In your latest example, if black flagged after the pawn had been touched it would be win under FIDE and USCF rules. If the black pawn had not been touched, it would be a win under FIDE but a draw under USCF.  In a nutshell USCF rules do not allow "helpmates" in considering if there is sufficient mating material on the board.

All of this is immaterial to the rules on this site which look at a simple piece count and the board is not taken into consideration. K+B is regarded as insufficient whatever the board position. K+ 2 Bishops (one light/one dark squared) is considered sufficient mating material.

I suspect your original diagram fell foul of the programming where K+ 2B is considered sufficient, but the program does not check the colour of the squares they occupy.

So black could be just about to touch the pawn in order to promote, flag, and get a draw under USCF?  So his opponent has to wait around with the clock essentially stopped, for as long as it takes for the guy to move, in order to possibly get a win, otherwise any claim will only give him a draw?  By running out of time the player gets awarded the best outcome without having to think at all about the position.  USCF essentially assumes best play in some situations once a player runs out of time.  

Back to chess.com, I wonder if it does any checks at all before determining the result.  For example, I wonder about the following position:  

Can black just wait for his time to run out to salvage a draw?  

In the game which prompted me to post, my opponent had something like 30 seconds left in a blitz game (can't remember if it was 3 or 5 minutes)... he simply stopped playing and let his clock run out to get a draw, when under FIDE rules he woulda lost...

I have already told you how this site deals with timeout/insufficient material. No point posting different scenarios, they all get evaluated the same.