You need to look at more than post count on here.
Firstly, look for feedback, you will see that he has 4 pieces of feedback on his profile, all positive.
Secondly, look at how long they have been on the site. Generally people who have been here a while will know members in real life and so can have plenty of people vouch for them. In this case the OP has been on here for 16 months, which is easily long enough for there to be people who have played with him in tournaments and so will vouch for him.