From chess.com support, the site follows the USCF rules on draw vs insufficient material in that if there is insufficient material* for a forced mate and the opponent does not have a forced win, it is a draw.
See also USCF vs FIDE by Greater Peoria Chess Foundation:
FIDE. It is possible to lose on time in situations that are a draw under US Chess rules. For instance, GM Friedel (IM Friedel at the time) lost on time with a king and rook vs. king and knight. Under the FIDE laws of chess, the game is drawn when one player runs out of time only if there is no legal sequence of moves by which the opponent could checkmate the player. Since there is a helpmate that allows a king and one knight to checkmate a player with a king and rook, GM Friedel lost the game. (Note: Earlier versions of this page incorrectly attributed this loss to GM Nakamura. The game in question is IM J. Friedel - GM S. Halkias, Bad Wiessee Open, Germany, 2007. See this story on Chess Life Online for more details.)
USCF. US Chess rule 14E (insuffient material to win on time) specifies cases where the game is drawn even if one player runs out of time. One of the cases listed in rule 14E is the opponent having only a king and knight (and not having a forced win).
*Insufficient material is defined by the USCF as if the opponent has:
- Lone king
- Only king and bishop or king and knight, and does not have a forced win
- Only king and two knights, player has no pawns, and opponent does not have a forced win