I think getting on the court quickly was a feature (hopefully) but was never the main selling point. The selling point is him being a super role player 3-D player that could allow some flexibility on sizing up or down. The defense was really passive in preseason but he did have one nice transition block in the game so I think its in there if he gets more comfortable.
Him not being NBA ready is a bummer but there are a lot of guys (upperclassmen usually) that are billed as "NBA Ready" that come in and struggle. Is it great... nah. As you mentioned its not like he's doomed.
For me those two things came hand in hand. I thought TH could be a super role player because he was young and already pretty good at the things that could make him a super role player. I didn’t expect him to be amazing right away, but I thought he had enough ability to get on the court right away. A wing who is just mediocre at both defense and hitting wide open shots has a good shot at playing for any team.