It sounded like Larson was just behaving like an edgy middle school kid. I doubt Larson meant anything by this, but he should have known better. "Public figures" with all these extra 0's on their paychecks get scrutinized like this for a reason. Really poor timing as far as slow sports news days, but maybe he'll be able to complete sensitivity training and all that without having to miss a race.
I don't think Larson should lose his job or be banned from NASCAR over this, but I wouldn't be surprised if they throw the book at him to set an example. Get him out of the spotlight for a while, make sure he goes through training so this never happens again, and please make sure he knows to treat any microphone like it's live.