First of, why are you making assumptions and statements when you
clearly are not informed/educated about most of these issues? Signature spam?
What kind of act to alter existing rules?
1 MB block size limit, or 4 MB maximum with Segwit is a
existing consensus rule. Any hard fork = change to the existing rules.
What kind of disruptive and damaging?
1) No viable replay protection.
2) Falsely labeling itself as Bitcoin, when 2x is an altcoin.
3) Damage caused by a combination of 1 and 2.
As I know, btc1 nodes has been added to the main GitHub and everyone could test it.
"Main GitHub"? No.
Wrong. Those are miners signalling support in their Coinbase. If you look at miners as community members, they and all the other support that 2x might have doesn't even come down to 5%.
As long as core developers and 2x devs follow the consensus, it's fine I guess.
The Core developers absolutely, unanimously (unless I've missed someone's statement), reject the cancer that is 2x.
"Consensus and support of 2x":
https://twitter.com/BitcoinErrorLog/status/918676222200102913