Probably won't matter. You would get so few items it would take forever for it to make a difference. Also high level players that don't care about exp would be winning all the rewards anyways, putting them further ahead. The solution will always be to sort by power level for events. And to force all events to give some exp that is unavoidable. Then freezing doesn't matter. Until something like that happens you should just try to freeze your own level if you can. Or at least level up as slowly as possible.