How is 「外野が無理に殻をこじ開けて」 related to 「自身の闇」 in this sentence?

Question

Context:

I am talking about the panel on the left in the middle section of the page.　The main character (highscooler) and his sensei go to see the main character's sister who has shut herself in a room, inside a pile of empty food boxes. They are going to possibly, get her out of that.

外野が無理に殻をこじ開けたところでその瞬間

さらに自身の闇へ閉じこもってしまうこともある...　あるいは

I think the above sentences translate to,

That moment when an outsider wrenches open the shell

Moreover there's a possibility that she has shut herself in the darkness of her soul

Then as per the page, the main character asks if the sensei is kidding because of the first line (above).

What I translated comes to me as pretty weird. Why would sensei say that and I feel like the two sentences are somehow connected but I can't seem to find much connection.

Answer 1

This さらに is not "moreover", but an adverb that modifies 閉じこもる. See this article for this ところで.

外野が無理に殻をこじ開けたところで
even if an outsider wrenches open one's shell,

その瞬間
at that moment,

さらに自身の闇へ閉じこもってしまうこともある
they may further shut themselves in the darkness of their soul.