No way to conclusively make that call until he's examined. I can think of at least 4 other possibilities besides pure racism:
(1) he was simply impaired at the time,
(2) he was suffering from the effects of his long term addiction and side effects of suboxone,
(3) he actually has a mental illness for which he was self-medicating to relieve the symptoms, or
(4) a combination of these.
he also had a website with a racist manifensto, wore apartheid flags on his jacket, burned the American flag, and told people he was planning on shooting up a black college a week ago...maybe he was mentally ill, but he shot up a black church, planned out the shooting, and was clearly a huge racist so....i still think the hate crime angle is more relevant.
i dont see a problem with that anyways. its not like that really hurts gun owner's cases. in fact, if he ISNT mentally ill, given the media's usual reaction to mentall illness, i think it might be better, because then we wont have to hear another "well, how did a mentally ill person get a gun? we need registration" line or whatever. i think the hate crime angle really makes it less likely to hit home for the average voter, because everyone knows someone on anti depressants, but no one "knows" any racists (that is, they wont acknowledge it if they do, because they only know pure, good people, right?). and the further it seems from everyday reality, the better. that's why there wasnt as huge a gun control pushback after the various muslim terrorist attacks here (fort hood and such), because it doesnt hit close to home. but adam lanza and Holmes...well, the crazy depressed person is more real, in way.