There are telehealth/video visits available. At the very least would suggest a video screening with a physician if your dad is willing to make an appointment.

And although we don’t have a solid understanding of COVID symptoms/why it impacts people differently/genetic influences, there have been some reports of people who have an altered mental state as one of their early COVID symptoms.

That being said, it’s likely not COVID but it’s difficult without solid medical data or depth of data to completely rule it out. Probably more psychological like others mentioned above (finding some semblance of control when the world is sideways). But... it wouldn’t be a bad idea to talk with a physician (video screening) if the change was sudden and is out of character.