Let me explain this really slowly for you. Say we take a TO after the sack and save the 25 seconds that burned off the clock. Then let's say that, with 8 seconds left Drew hits Moulds over the middle of the field and we have no time outs to stop the clock...tick, tick, tick...we lose.
Now, Let's do some math. If we saved 25 seconds by calling a TO after the sack...and there were only 8 seconds on the clock when Moulds caught the ball would that play have even HAPPENED if the TO hadn't been taken after the sack? (hint: this isn't a trick question, or a particularly hard one). The only way your arguement makes sense is if there are more than 25 seconds left on the clock after Moulds makes that catch and for some insane reason we can't get downfield to spike the ball in that time.
You have the weigh the difference...does it take more time for the offense to get down field to spike the ball at the end of the game (when they all know before the snap that they have to do so) or does it take them longer to get back to the LOS after a sack (when nobody realizes for a few seconds what happened and the WRs are all downfield), get a play called, and snap the ball?