If you foul in that situation, you stop the clock and give "free" points to the offensive team. They can make the first free throw and follow-up a miss on the second one.
Coaches know the statistical probabilities of winning in that situation while playing "straight-up" defense rather than fouling. Both Romar and Calhoun prefer the philosophy in that sitch of just playing straight-up defense. It works most of the time and nobody questions the philosophy. When the other team makes a long three to tie it up, all the "backseat coaches" question the philosophy. If Washington fouls and ends up going to O.T. because of a made FT and a follow-up basket (or losing after a made FT and then a pass out for a 3-pointer), there would be even more backseat coaches.
It's always funny to me to be with a group of refs to watch a basketball game. They spend most of the time questioning the coaching decisions. Then they get upset when the coaches question the reffing decisions.
Z