Hmmm... are you simply redifing 'good' to mean 'being a rightwinger'? If so, of course you are right by definition.
And I can do the same: there are no flying mammals. (Because I have redefined 'mammal' to mean, 'not able to fly'.)
But if we use one of the normal meanings of 'good' -- however you want to define it -- then, you are mistaken. Please think again.
Here's a test: I could pick some people I know personally and tell you everything about them, except for their political views. Some would be conservatives, some liberals ... two of them, in fact, are hard-core Marxists -- one a Trotskyist, the other the head of the Communist Party in his city. You would not be able to tell who is who just from their non-political characteristics. They're all 'good' people, even if the consequences of the views of the Leftists, especially the Marxists, would be disastrous.
And here's the problem with that attitude to Leftists:
it keeps us from destroying the Left. We need to
argue with these people. We need to present facts that undermine their beliefs, and demoralize them, and then make them think again, and change their minds. This never happens overnight. It takes years, and above all, the impact of events.
We need to open up the contradictions within the Left -- say, between the ones who believe in Free Speech, and the ones who have the fascist attitude towards Free Speech.
Between the ones who actually want to help Black children get a decent education, and the ones who couldn't care less.
We need to pull some of them towards us.
Can Leftists become conservatives? Can Saul become Paul?
Well, of course they can. Half the founding members of the editorial board of William Buckley's
National Review -- for decades the premier conservative journal in the US -- were ex-Marxists.
Here are some Leftists who became Rightists.
ttps://en.wikipedia.org/wiki/James_Burnham
Second Thoughts on James Burnham - Wikipedia
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
And these are just the 'heavy artillery'. I can name you lots of small fry who were radical leftists in their youth, but who wised up as they got older. As Churchill is supposed to have said, 'If you are not a socialist when you are 20, you have no heart. If you are still one at 40, you have no brain.'
Their morality didn't change. Their values didn't change. Their political views -- their views of the proper means to making their values reality -- changed.
It can happen again. But not if we just reject all Leftists as evil people or cultists etc.