Suzanne - definitely no, blocking a user does not remove them from your tree. See: http://help.geni.com/entries/21453997-how-can-i-block-another-geni-... for a list of what Geni currently says it does.
Note that it is dated May 16th of this year. For months before that, the FAQ said Blocking would also prevent the User you Blocked from editing the profiles you managed, even tho that was no longer the case.