ubiquitin,
“I agree it is wrong for late comers to ask people to move, though even thenIfthey ask nicely AND ( cant stress this enough!) provides a seat I think it could be justified but not as easily as the guy who comes on time.”
Good point!
Another point – Most don’t realize, that Makom kavuah applies to Tefilas Shemonah Esrei only (as all terms of Tefila in shas), therefore, where there is no other seat available etc., he can (and should) ask nicely if he can take his place by Shmonei Esrei, i’m sure the guest won’t mind moving over for the few minutes.