His classmates all said that he was a political conservative in highschool. Not just somewhat conservative, but reflexively so about everything.
Crooks' father was registered Libertarian, which in US politics often is just another way of saying conservative and suspicious of government. And just because his mom was registered Democrat doesn't mean much. In the Midwest in particular at one time there were alot of people that register as Democrats because of social class or ethnicity.
It's important to not politicize an event like this. Most presidential assassins in recent years have been motivated by mental illness and insanity, not politics.