Okay, so given that:
A) The wheel axle can't be installed in a way that the tire can "lean" off of vertical (though it can be installed so that the wheel won't track straight);
B) It doesn't seem likely (absent further information) that either the swingarm or wheel are bent;
C) The rear of the bike was taken apart and reassembled
Let's see if we can figure out what might have gone wrong. Here's the parts diagram:
The swingarm bolt passes through a tube (42036) that sits in the swingarm. At either end are an oil seal (92049) and a bearing (92046). It looks like the tube rides in the bearing, the bearing fits into the swingarm, and the oil seals keep dirt out of the whole shebang.
So what happens if we leave out one bearing? Seems to me that might produce what we're seeing.