A "bot" refers to a crude AI script that (badly) replicates human player behavior, presumably for the purposes of farming. My guess is they had trouble wrapping their heads around the idea a real live person would
choose to run back and forth from Point A to Point B in the middle of a firefight, (usually) not firing his weapon and not killing anyone, just tagging the door if he reached the end of his run and going back the other way, over and over again. Not even earning XP, just running back and forth, back and forth.
You'd have to be a bot or crazy, I guess.
Didn't stop most of them from trying to get that free kill though. Especially the ones that complained loudest. Someone even typed "if you're not a bot then stop running and kill someone"
after I stopped to pop an ulting Junkrat as I was running along the trellis in Widow's castle. He was right below me, I had to.
And then I threw myself over the edge into the water, to reset to 0 kills.
:)