I’m in academia (though thankfully outside the IS system now, which is brutal). As
@RickshawFan said, an Assistant Professor would definitely oversee all types of students from undergrads to PhDs.
But I think it would probably be unlikely that these two cases are connected because of the departments are unlikely to have much overlap even in undergrads. I’m in a health sciences department and I couldn’t even tell you where the business school is. Do we even have one? No idea! I only know a few colleagues outside my own research institute and they’re In related fields.
Undergrads do take courses more widely but I think it would be unusual for someone to be taking both physics and business classes - and be disgruntled enough by both professors to harm them.
I would assume this is something personal if connected (though personal networks rather than professional ones), or just entirely coincidental.