Though, is this a minor infraction? If this could effect the other clan results if Otterycat beats them, it could effect all of Clan League.
To me it is. It's a misinterpretation of a small detail, of an already confusingly worded rule.
Otterycat last played CL for 101st in April of 2018, which has been a long time. There is also no guarantee Ottery's spot if played by another player would be better or worse than Ottery, and is a pretty poor argument. It can also be said that forcing 101st to surrender would give the clans Ottery is playing an unfair advantage as well. In the end of it this league can't be pushed into being 100% fair. Boots, mistakes, variations in level of play and substitutions alone make sure of that.
Well, if that's the case, then warn them! It is simple! You can't let a rule-break just slide
I won't be the one making this decision as it is up to the ethics panel to decide, I'm just stating my opinions on the matter.