Gonna have to take the other side on this one.
In my unprofessional opinion, I would say the clowns change in behavior is most definately related to the recent disruption in it's world.
Having a host anemone for over 2 years - that clown developed a behavior pattern - each and every day, mostly the same thing.
Eat, sleep, lay around in it's anemone for protection, you know - clownfish stuff.
Then bamm! No more anemone, no more buddy, no more safe haven. The clown was now out of it's normal 2 year old routine and developed a new routine.
I never asked a fish this, and if I do, I give you permission to call the guys in the white coats to come get me - but I would bet that most all fish have very basic needs, and do live by a developed schedule in our tanks.
There just ain't that much for fish to do in there ya know. Swim around, eat, produce wastes, sleep, pick at stuff on substrate and rocks, and interact with other tank mates and us - the great provider and caretakers.
The change in aggression towards the puffer may be short lived - or may have become the clowns new thing to do now, even though you got it a new sebae to hang out with - it may just find that pestering the puffer is fun thing to do.
Probably just a normal, evolved, instinctual response though.
