If I have a player who is eligible to play 12U but chooses to play on a 14U team, can that player play as a guest in a 12U tournament or is she locked out because she played for a 14U team?
Generally speaking, ASA's classification rules only apply to championship play (e.g. qualifiers, nationals). There shouldn't be any issues as long as she doesn't guest for another team in a championship play event, which she shouldn't do anyway because of ramifications with redlined (i.e. frozen) rosters.