I know it's a free roll but gimme a break

So NBA told me about the free rolls for the WSOP on PP. 3500 people and top 50 get into a staellite to try and get into the WSOP ME. So I play in one and were at about 1000 people left. I have a little over 15,000 in chips and I raise up to 900 utg with AK (blinds 150-300). The buttons calls me. Flop comes A72 rainbow. Pot is 1950, I bet 1000, the button moves all in for about 13k. I'm like did he flop a set, get 2 pair or ace weaker kicker. I sensed the latter and was correct, he turns over A5. Turn is a 9 and the river...is a 5. WTF. I asked him in the chat, you didn't think I had an ace raising utg. He said nope. That's poker folks or at least on-line poker. I busted out a round later when my AJ all in met up with AQ. I wonder if this tourney cost money to enter if he would have played the same way...my gut says yes and that is what is really scary.