I think you’re answering your own question here.
Your blunt coworker has to explain himself or risks being taken as rude by people who don’t know him. You yourself couldn’t determine if he was being rude to you without some additional context.
Without further context, you don’t know how to interpret an email that says where is my spreadsheet motherfucker.
In both cases, you’re saying further social cues are needed to determine if someone you don’t know very well is being rude or not. Hence, why people emailing people they don’t know very well in a professional capacity include niceties to convey context and tone.
The cops personal state of belief doesn’t matter, they just need to be able to show probable cause.