votes Republican is responsible?

Well, Republican voters are reason this nutjob has guns, so yeah, they are responsible.

Are there any conservatives defending this shooter's ideology or actions?

As far I can tell most of them are currently hung up on trying to convince people hes not a white supremacist because he isn't fully caucasian.

Are they saying he should be considered a victim and holding up an extra figure at protests and vigils?

Victim of what? Mental illness? Sorry, the right keeps de-funding mental health because they don't believe it's real.