Bitmain fucked up, with no malice as is revealed by the open nature of their code on github. Malware writers do not publish their code for the whole world to see.
This is a false conclusion fallacy. Just because they have published their code on GitHub that premise does not in any way follow to a logical conclusion of benevolent behavior. The backdoor exists in all miners, and can be exploited by malicious actors. Whether that actor is going to be Bitmain or someone else is not of high importance.
I didn't say their behavior is benevolent. I said they fucked up, meaning it was stupid of them to leave this backdoor in there, although clearly their intent was not malicious. They admitted it was stupid of them and every BU supporter should acknowledge the same. This failure does not make Segwit better from the investing standpoint. Core supporters can spin this any way they like, but the fact is Segwit does not suddenly become our savior because one man on the competitor team screwed up.
From the investing standpoint BU, Segwit are too controversial changes to bring to a safe haven crypto. If Bitcoin is willing to lose its safe haven status, I am afraid it will become not relevant much sooner than if it kept the status quo.