I don’t like leaving potential commitments up in the air. I prefer to either commit and add them to the schedule or decline them. Otherwise the request for commitment simply becomes an additional item to track and requires more cognitive load.
This also goes with my principle that indecision is almost always worse than a bad decision. Simply choose the best option, if needed most can be reversed if needed.
If there is a circumstance that may hinder the commitment, let the organizer know and put it on the calendar.
In short there is no reason to keep commitments up in the air. Be decisive.