How to interpret this joke: 釣られたからって引きこもってやんのテラワロスwww

Question

In episode 12 of Death Note Light is watching a video sized by the police of the second Kira and gets angry at how this Kira is tarnishing the real Kira's reputation, to which THIS blog author replies with a short reflection from when Lights got tricked into killing who he thought was L:

あのー、すいません月さん。あなたが抱いているキラのイメージってどんなものなんですか？　これまでマスコミで報道されたキラの行動というのは（偽キラの一件を除けば）安い挑発に引っかかってリンド・L・テイラーを殺し、しかも肝心のLには手を出せなかったという公開羞恥プレイだけなんですけど。その後についても、本人としてはLや警察をあざ笑うかのように正義の裁きを行っているつもりなのかも知れませんが、醒めた一般人（例えば俺）には「釣られたからって引きこもってやんのテラワロスwww」とネタにされているのではないか、という可能性も少しは考えましょうね。

This is the part I'm having trouble with:

その後についても、本人としてはLや警察をあざ笑うかのように正義の裁きを行っているつもりなのかも知れませんが、醒めた一般人（例えば俺）には「釣られたからって引きこもってやんのテラワロスwww」とネタにされているのではないか、という可能性も少しは考えましょうね。

I'm trying to interpret this as:

"Even though Light has the belief he's imparting justice as if to mock L and the police, for woken people like me, isn't there a joke that says "I may have been tricked but you're f**king staying indoors"? Think about that for a minute.

What's the correct interpretation of this joke? I know that てやん is a vulgar form of ている, (hence I'm using an expletive) but I don't see what's wrong with L staying indoors. Am I missing something?

Answer 1

• This ネタにされている does not mean there is such a recurring joke. This ネタ just refers to a "(funny/amusing) conversation piece". The sentence is saying Kira's story is used as a good conversational topic by ordinary people, or simply, people are rumoring about him. The author is saying cool-minded people must understand Kira has already been driven into a corner.
• The implication of this 引きこもる is "to run and hide (like a coward)" or "to keep oneself hidden (until people forget about him)". The content of the quote is like "(Kira,) You are hiding yourself after being tricked and noticing you're in danger!".