Well, define 'failure'. Minor outages like the one you are talking about were happening from time to time long before Musk bought Twitter, and it even suffered long outages frequently - remember all those fail whales?

I meant that there will be no catastrophic failure that will permanently (or even for a few days) stop Twitter from working at all.

failure. noun. with no security team, hackers are able to get in easily.

everyone's DMs leak, all the anonymous accounts have their identity revealed, and all Twitter's clients (advertisers) have their bank account info made public.

Yeah, I don't think anything remotely close to it will happen, unless some of the fired developers have left themselves some backdoors which they'll give (sell) access to it to someone.

does this stuff happen automatically? is there a robot that goes out and reads about all the new zero-day exploits and patches all the software without human intervention?