Tai is skilled in telepathy, and knowing how much emotional turmoil ben had he could sense it and wanted to be a potentially positive person in his life. Not just another student that ben feels like he has to stifle who he is. Tai sensing his alienation (though maybe not all the details of "he thinks his parents are scared of him") and knowing hes lukes nephew, the prized student, all eyes are on him and some may not be very admiring, and he wants ben to be able to have a break from all that
Him sensing the underlying darkness in ben and not shying away from him, after all...thats his friend, hes not going to just give up on his friend