If a horse kicks out at you at feed time this is a pretty serious display of disrespect to you. Your actions in response are not wrong, it's just that they need to be much more immediate.
If it had been me, I would have dropped everything and come after that horse like I was going to KILL it. If I had a lead line in hand, I'd swing the end down hard on his butt (assuming I have enough room to be out of kicking range). If not, I'd pick up a stick or I'd take off my coat or use whatever I could put in my hand in ONE second and go after him. Yell loudly and make him realize he just kicked open a hornets nest, so to speak.
After I had moved him around (loose, in the pasture if that's where you are), then I'd go back to the food, put the grain in and stand over it like I am the lead horse and nobody eats til I am done. Do not allow him to approach it. Go after him like a lead horse would, if he approaches. When he is perfectly cowed and willing to stand submissively off to the side, step away and let him have it.
You need to practice moving him off of you every time you come in to feed him. He must stand a good 6 to 8 feet off of you , not have his ears pinned and wait until you put the grain in, stand over it and "own" it for a bit, then turn and walk off.