I don't see getting to the rim as being the same as running a post up, low post offense (inside out or whatever you want to call it). Post up plays can be part of the overall offense but the shots at the rim tend to come more from another player penetrating or from off ball movement (back cuts, things like that). Or pick and pop actions.
As to the Celtics, I don't see the need to have a center that you can run the offense through. Post up, draw the double, and so on. I can't think of any team that has that. You look at NYK and Towns can hit the 3 and Brunson creates dunks through penetration. That is how they do it. BOS does not have a guard that can penetrate like Brunson.
For BOS, Queta is very limited offensively. He can dunk, but not much else. Vucevic never got in a groove, so I am not sure we know what he can do, but whatever it is, he was not doing it for the team last season and in the playoffs. I think he could be an effective pick and pop guy or pick and roll to the hoop guy. I don't see the need to have him post up other than opportunistically when there are certain match ups that result from switches.