You may not like what he does, but he wasn't doing anything illegal that we know of and he certainly didn't deserve to be murdered for it.
His right to own those guns is protected by the same document that guarantees that you have the freedom of speech to call innocent victims 'morons' without being thrown in jail for being an asshole.
____
When the second amendment was penned, there was no such thing as a semi-automatic rifle.
There were single shot muskets which took like 2 minutes to reload. That's what they gave us the right to bear.
That's worthy of note.
But on the other hand:, of course, the point was to make sure that the citizens could not be oppressed by their government. So if we are only allowed to carry single shot muskets. And the government is using automatic assault rifles and tanks, then the government has nothing to fear from it's people. Which is bad.
In addition. America is not an island-nation like Japan. So banning guns would not work as well here as it does there. Not counting the millions of guns already in the country, more can easily be smuggled in on land from neighboring countries. So the bad guys will still get guns no matter what.
If guns were harder to get, then 20 year old lunatics wouldn't be able to shoot up schools. Proffessionals still could, but at least a lot of the random nutjobs would be weeded out.
I don't have a good solution. But I think it's good to understand both sides fairly.
And I don't know why he was killed. But the fact that a gun rights advocate was shot in the head is no more to the point than if a marijuana legalization advocate was hung by a hemp rope.
You may think that if gun control was better than he wouldn't have been shot. That may be true. Or he may have simply been shot illegally. We don't know the motive, but if the person wanted him dead he'd probably be dead regardless.
True, his guns didn't protect him. But neither did the local police. And since sometimes the police fail, it may at least be nice to know that he had the option of defending himself.