Dealing with a brainrotted colleague

Hey guys. I'm looking for some advice which is extremely non-technical on something I'm sure many of us are either already dealing with or will be in short order. I joined a small company some time ago as the sole sysadmin. I had a big corporate job where all I was doing was endpoint/MDM and I was bored, and the company was also tanking itself which helped me make my decision. In fact, they started massive downsizing two weeks after I left. Also, a 20% salary increase came with the new position so... Anyway, I'm the only sysadmin at this company. The guy who did my technical interview was cybersec. His questions were suspiciously basic - I'm sure anyone who's done compsci 101 could answer 90% of them. But I thought nothing of it - he's cybersecurity. His expertise was elsewhere and he was doing what he could. Fine by me. Fast forward to today and over time I've seen some interesting patterns with this guy. Weird decisions and requests. It started to click in a Teams meeting this week about an upcoming migration. One I've done elsewhere several times. I was me, the cybersec guy and my director and I was explaining what we needed to prepare and what issues could arise in our specific environment (which I set up mostly from scratch). And then the cybersec guy did it. He contradicted me, prefacing his statement with "But ChatGPT says.." Womp womp. Suddenly it made sense. Why he'd been making weird changes. Asking \*me\* questions he should have known the answer to. Approving random pre-alpha GitHub apps for deployment. Having this how him vendor changelogs on firmware updates (e.g. Fortigate) because he thought the new version number was an older build and seemed unwilling to just friggin google it. I don't think he knows what he's doing. I think he's basically an LLM meat-puppet - no thought, just a tunnel straight to ChatGPT in place of a brain. Now, this is not to say I am wholly against the use of LLMs. In my case especially as the sole sysadmin, I use Claude to speed up searches rather than parse through tons of documentation for a single item, have it help me identify items in logs CMTrace can't display properly or feed it my (sanitized) PS scripts when whatif isn't giving me the output I expect and I can't figure out why. They have uses. Entirely replacing institutional knowledge and experience is not one of them. So, how do you deal with a coworker like this, especially when they've been there longer than you and are more 'trusted'? Most of the time he seems to be doing a lot of not much, which tbh is my favourite state. I've gone in behind him to sort out our firewall, endpoint security etc which were throwing warnings he didn't seem to notice. Everything is fine until he's forced to do something, usually by my director asking him to approve or look into something. Then I kinda put my own projects on hold until he's done so I can clean up after him - not to help him keep his job but to make mine easier. Do I keep my head down until the difference in our tenure is minimal (e.g. he was hired six months before me, so at 2-3 years the difference will be negligible)? Or do I just have my fun with the work I'm doing, learn all the tech I never got to touch in a big corporate environment, and resign when his quite literal absent-mindedness causes a catastrophe I don't want to deal with?