Oh dear, I'm not sure how this is going to go in the long run, but okay.
To discuss the specific legal consequences in a given situation, one would need to know the circumstances out of which the happenings arose. That is to say, anyone would require all the salient information which could bear on a discussion of the circumstances because such inquiries are necessarily fact intensive.
What facts specifically? That I cannot say because I have a complete lack of information on any facet of this case so I don't even know where to reasonably to start in terms of giving you a list of what more we'd need to know.
I suppose the best I can do is just say, at this moment, we'd need at least some information as opposed to the situation in which we find ourselves now: a complete lack of any information.
By the way, saying that:
1.) it wasn't you involved,
2.) you don't even know if it was supposed to be an interview, and
3.) they were yelling at him
really isn't information. It's akin to saying, "Yesterday, I went somewhere and saw some people. And yeah, that's what happened." Sure, it's "talking", but it provides no real information.
For instance, I have no reason to even suspect you were present at the event. I have no reason to believe that you were privy to any of the inner-workings of the situation. There is no good reason to call into question the --well, I presume these they people were police officers despite there being no suggestion they were-- yelling bit. I'm not aware of anything which specifically requires supposed police officers to at all times be civil and use moderate language and tone when interviewing someone as a matter of law. It might be departmental policy for reasons of PR, but that hardly rises to an issue of constitutional concern.
Simply because a police officer is rude doesn't mean there's some constitutional violation. As I was fond of saying to people, "I'm here to protect your ass, not kiss it."

