Happens all the time and the only reason anyone cares about this time is because Musk. If Twitter pays a FMV to Tesla for any resources, and as long as the Tesla board doesn’t care (which they won’t), this is a non-issue. Doesn’t matter what kind of “firm” Tesla is.
If the CEO of Ford used Ford resources to purchase a rental property for themselves, people would definitely be talking about it. I would even flip your claim and say the only reason people are dismissing this is because it's Musk.