No kidding. Nobody was asking him to buy a book or commit to a longterm campaign. It was a one-off playtest.
It is silly & rude to his group. Forcing your gaming group, to NOT play that night due to his lack of flexibility. It was a one shot game, be a sport. He has not spent a dime on the game, also denying himself to give negative feedback to WOTC. Giving up the chance to complain how he disliked D&D next for the next decade.