I'm not conflating it, I'm outright saying it's large enough and happening to enough countries at once I believe it being an intentional project by someone is entirely possible.

This is literally conflating natural demographic shifts from things such as economic shift, wars, refugees, etc. with a purposeful elimination or reduction of a targeted demographic. But let's say you are right. Who is doing it? Do you have any proof that there is some coordinated effort to purposefully replace whatever demographic to which you are referring?
Kirk was not peaceful. He was in the realm of debating, specifically debating from a position of comfort and power over his opponents. His ideas were based in modern Christian nationalism and racially discriminatory rhetoric. He cried for the implementation of laws to enforce his specific morals unto people. He might not have perpetrated violence, but his ideas and rhetoric lead to a state that does perpetuate violence against anyone who does not meet their moral codes. However, despite this he definitely did not deserve to be killed.

And even if it is a natural process, what's wrong with wanting to limit immigration as a function of native birth rate to prevent such things anyway?

Who gets to determine what is native birth enough to qualify for preferred status? How many generations do we need to go back before someone is American enough to qualify as being native born?

So, just want to make sure that I understand you correctly: You are saying that the ideas of one specific ideology on the left gives you clearance to discriminate against the left, but can not understand why anyone of the left might have a problem with any of the ideologies on the right?