First, what the protestors in Tianamen didn’t do was break into the government buildings with the intent to kill specific members of the government and to overturn the results of an election to install a leader of their own choice. That happened in 2021.
Also the death toll in 1989 was much much larger.
If you want a better US example, maybe something like the killing of striking mine workers in the US although I’m struggling to find an example of a single event that comes close to the scale of Tianamen.
I wouldn’t find it surprising that some of the protestors suggested something like that. But the fact is that this didn’t happen, and the protestors (and bystanders) who were killed were not attempting to break into a government building, attack government officials, or overthrow the government. If they were killed by security guards while attempting to rush the palace, that would be different.
The protestors did fight back. But that’s a way higher number for military deaths than I’ve seen recorded anywhere, and thousands of civilians (including a lot of bystanders) were dead before tank man did his thing.