What we do in our office, to make sure everybody feels supported, is to have rainbow decorations, and badges and stuff for people to wear.
You could wear a rainbow badge, to show that you support, and so he knows to feel safe. You can also encourage others to wear a rainbow badge, or lanyard or something else, to show that he can feel safe.
If you pasted something long, you could possible switch to a terminal (ctrl+alt+f2 or something), and kill the process.
Or you could grab another machine, and ssh into yours to kill the process.
FreeCAD