So Mr. Wick was under a blood marker and had to honor it, or an old guy tells him everyone will kill him. Then he honors the marker, and the markers holder put out a contract on him so everyone will kill him, and now the old guy says it doesn't matter?
Why not just ignore the damned marker then? What, is there super duper assassins 100 levels above all the city super assassins that only get called into play if a marker isn't honored?
That's part of the rules. The hotel cannot refuse services unless the one asking for the hotel services broke said hotel rules.
Think of it like this. Ever watched Highlander? Remember that churches were considered holy ground. A place we're immortals can find refuge. Not even the Kugan, the most vile in all the series broke that rule. Lest he faces the consequences. That rule was removed for endgame for some reason.
Anyway, even cold blooded murderers needs a break from other cold blooded murderes once in a while.