I agree - he still has plenty of length off the tee to get to most par 5s in two that at least the top 1/3rd can get to. He definitely had the length to get to 17 yesterday with a good drive and he had to take the chance being two back. He wasn't going to win without going birdie birdie on the last two and best way to get a birdie on 17 is reach the green in two - with a great shot, he could go eagle birdie and put a ton of pressure on Koepka. That was his only play at that point on Sunday. He also had his so many good drives on the back nine that he had to go again - but I think the pressure put him back into the bad swing he had on the front nine.
If he had taken an iron off the tee and ended up with a par, everyone would be all over him for not trying to get to the green in two. Again, it was his only option at that point on Sunday.