First of all IMO LA is a natural center. He's 6'11, strong, and has a great wingspan. He can punish players in the low post and can shoot over them from the elbow.
Secondly he dominates most centers. The only one who he doesn't dominate is Howard but lets see how he comes back from back surgery and if he pouts half the season. LA vs Bynum is a fairly equal match up.
Thirdly, position names are outdated. There are low post players and wing players and even that line can be blurred. You don't have any control of the other team having their tallest player guard LA. Likewise it makes sense for the Blazers to have LA guard opposing "centers" because it is a weaker position overall. Who is the easier defensive assignment, deandre jordan or Blake Griffen? Joel Anthony or Chris bosh, Anthony Davis or robin Lopez?
Finally look at the greatest centers of all time? Do you think the 6'9 Bill Russell told Boston fans he wasn't a center and didn't want to be bothered with guarding the bigger wilt chamberlain because he didn't want to have excessive wear and tear on his body. Do you think Kareem, who was a finesse player, ever said he wanted to be a forward and not guard centers?
Speaking of Kareem, he has been quoted that the one center in the league who plays similar to how he plays is LA.
"I know there's one guy that posts up in the same way that I used to," Abdul-Jabbar said. "He plays for Portland:LaMarcus Aldridge. He shoots a hook shot and he is a very effective player. He scores inside and turns around, goes out to 12 feet and shoots jumpers and is really able to do that."
LA makes the team better when he plays center.