Creating a repository on the official account of your employer is not an innocent joke. Media will pick up on it expecting content and when it doesn’t show up/gets removed, you’ll have a whole bunch of loser journalists writing news stories bashing Elon.
In fact, any action that appears to have been made on behalf of a company is not and will never be considered an innocent joke. I’m sure you’ve heard everyone disclosing something they say or write is “their own opinion and not of their employer’s”. Now please show me that kind if disclosure for this repo and then maybe it can be considered a joke.
If you think doing this kind if thing is OK regardless of context, then you’re in for a world of surprises when shit goes south for you.