I've just watched a video where they mention that very point.
Firstly, it's irrelevant because they weren't tackling him because he was armed as they didn't know what he was until they had pepper sprayed him and beaten the crap out of him.
Secondly, yes, it's a requirement to carry ID when you are carrying a gun. Do you know what the penalty for that is in MN? I'll let you look it up for yourself - as a clue, it's not summary execution by the side of the road!
And, from what I understand, not having ID doesn't make the carry unlawful. The offence is one of not having ID, not unlawful carry!