You mind lending me the crystal ball you used to determine that? Maybe without stopping the clock the Texans score earlier, and the exact same scenario plays out with more time, not less. Maybe instead of conceding the first down, they make the stop 2 plays in a row (which is exactly what they did at the goal line before the TD) and force the FG, and end up with the same amount of time on the clock - winning in regulation with a TD.
Or maybe there's a botched snap and the Titans recover. Not a likely scenario, so you don't take it into account when you're coaching to win. The odds of Texans not getting a 1st down after 2nd and 1 is extremely low. And if they don't get it on 2nd down, they get it on 3rd down and they just added 2 extra plays. The odds of them running the ball on 2nd and 1 is extremely high. The odds of passing (and not running the clock) on 1st down is much higher than on 2nd and 1. Give them the 1st down and try to stop them. If you don't stop them, at least you saved 40 seconds.
There are actually models for this stuff, that determine win probability after each play. ESPN's doesn't appear to show the penalty as a play on their graph, but pre penalty it was 82.7% (TEN) and post the next play (incomplete pass - which obviously would lower win probability) it was 78.8%. The penalty couldn't have been much of a boost in win probability.
"According to EdjSports, a data analysis company that works with NFL teams, the penalty actually increased Tennessee’s win probability from around 17% to around 22%. It was a very significant aspect of a very significant drive because it saved the Titans time and a timeout.
The penalty helped for a few reasons. On second-and-1, the Texans were likely to convert on one of their next two plays. If they had converted on second down and stayed inbounds, they would have snapped the ball next on first down with around 2:20 remaining – or with the Titans having used one of three precious timeouts."
https://sports.yahoo.com/titans-intentional-penalty-mike-vrabel-texans-161114454.html