Switching regiment during the league isn't. This however 'Maybe they left their Regs for that match, then left 79th after it to join back into their former reg' is excessive.
So you are allowed to switch once however you arent allowed to switch twice, then it should be stated like that in the rules
since as you said, everyone values it different
the rule 1.2 leaves room for the admins to judge differently which includes whether they like the person or not since it depends on them if it is excessive or not.