Not quite is he saying that he fixed the fights. Just that he arranged them, as opposed to allowing someone who could have beaten Ichigo to fight him - Such as explaining why such a powerful Hollow showing up when he was fighting against Ishida. It makes no sense to just suggest he fixed it, as Ichigo DID grow in power and Aizen was discussing using him for his 'raw power', which is illogical it's self if Aizen was planning on winning all Ichigo's fights for him. Hell, even the 'Don't disappoint me' comment he made after the swing implies that he feels he knows what level Ichigo should currently be at.

Anyway, still a cheap cop out - Because Isshin isn't allowed to kill Aizen anyway because he's not the main character, and his appearance, IMO, is actually more bad writing than clever writing. Why hide out while this fight happens if he just plans to kill Aizen?