rack block is no big deal. as soon as they stop doing reps, i'd slide right in and grab my dumbbells.
at my old gym there was this short asian guy that would take a flat bench, an incline bench and 2 machines to do his circuit. he was in the middle of his thing when this big old dude wearing the american flag short shorts starts pulling the plates off the bar on the flat bench. little asian dude was heated and started complaining to the old man. the old dude looks down and chuckles and pats the little guy on the head, nudges him to the side and keeps taking the plates off the bar. i think asian dude packed it up and went home