I would not go in with a whip, this is unnecessary.
If he tried to bite as I walked past I would slap him hard across the flat side of his muzzle.
When I go into a stable the horse has to move back to give me room. This is not just at feed time but at all times. If a horse charges me at feed time or is totally disrespectful then he gets the feed, still in the bucket, wrapped around his neck, chest or, if really bad, his head. I will then chase the horse so he is going backwards around the stable until he realises that I mean business.
he can, for that feeding, pick it off the floor.
I will not tolerate ill manners at any time and feed time can be dangerous if they are not corrected.
I have six big young horses in a loose barn where they get fed. They learn that they have to stand back whilst I put the feeds into their pails, if they do not then they get chased and know that I mean business.