I'm more inclined to think it was intentional than I was before seeing that slow-mo!
Boss puts a hand on Impey, appears to grab a handful even, moves up level with him and then (at around 5 secs) suddenly drops back. Why? No idea. He appears to have space but can't really go through and past; maybe he thinks it's no place to be?? But in that slowing down process, Boss seems to pull Impey back too. Boss looks back and to his right too, whatever that might signify.
I can't work out why he'd might want to pull a rider down right in front of himself, that makes no sense. But I can't work out what he was doing either. It looks to me like he has space, so I can't see why he'd even reach out to touch Impey.
The thing that looks damning to me is that Boss seems to not just touch Impey but grab his shirt. Grab it and then pull back. It doesn't look good.