Thank you for expressing your concern.
I have wondered the same thing myself. The internet is a different medium than old-fashioned newspapers. Newspapers frequently posted op-eds and letters to the editor that reflected differing points of view.
The internet and Google make it possible to self-select what is read, thus creating a kind of confirmation bias and immersion in an echo chamber. It is easy to be sucked into an extreme view if no dissenting views are available.
While I tend to favor free speech and might argue that Mr. Blow's rants would probably have no effect on his decision to become or not become violent and that knowing what he thinks at least forewarns us--and maybe the FBI is on to him because of these posts-- I am not sure that specific features of the internet might not weaken these arguments.
But modern cable news is also an echo chamber--true of both MSNBC and FOX.
As for Caitlyn being responsible if Joe Blow does something awful, since she has not encouraged violence against anyone--as far as I know--I cannot see how she could be responsible. Especially since Joe Blow probably formed his views independently of anything she has written.