Withdrawing a protest?

There was a protest the other night, and the protestor now wants to
withdraw the protest.  To the best of my knowledge, it was a
****t-starboard with no contact (and thus no damage or injury on either
boat).  Apparantly the race committee is refusing to allow the protest
to be withdrawn.

RRS 63.1 says, "...The protest committee shall hear all protests and
requests for redress that have been delivered to the race office
unless it allows a protest or request to be withdrawn.".  Is there any
guidance for when it would be appropriate for the PC to refuse to
allow a protest to be withdrawn?