OPnet.org can do everything Citrea.xyz wants to do
Citrea can already do everything they want to do with no changes made to Bitcoin Core or anyone else.
The thing that kicked off all of this drama is that a Core dev read Citrea's whitepaper, saw the construction that they were going to use, and said "wow that's dumb, you can do better if the OP_RETURN limit was higher". The whole point is that the current construction would insert 2 unspendable outputs into the UTXO set and they were doing this in order to work around the OP_RETURN limit. And the discussion started with the thought that if the limit were lifted, Citrea could be convinced to just use a single OP_RETURN instead.
Are you sure that Bitcoin Core contributors didn't write or help write Citrea's whitepaper? "Put it on paper and we will get it pushed live" type of deal." Because it is absolutely giving that vibe.
Do you or anyone you know have a financial interest in Citrea?
There isn't a BIP; this isn't a BIP-able change.
Ah, duh. Gotcha.