I'll bet you'll hear from dozens of moms that their little ones do this. My daughter did, and now my grandson, too. There's instant magnetic attraction when you combine mommies with food preparation. Plus, it's dinnertime and everybody's hungry. Plus, your son is big enough to be genuinely interested in the fascinating and complicated things mommy and daddy get to do. And if you were that short, wouldn't you want to be up where all the interesting stuff is going on?
Can you give a few minutes of your prep time to including him in your activity? Just plan for it as part of your kitchen activity. It may seem inconvenient and intrusive, but that's what it is anyway, and neither your son nor you are getting any pleasure from the current situation. You can make it happier for you all!
I agree with Marda that you might try a high chair near the stove, close enough for him to "participate" by stirring a bowl or pan (bigger- more "special" – than his usual food bowl), with maybe a few slices of banana, a broken cracker, cheese, water or milk, shredded wheat, some nutritious leftovers, whatever you wouldn't mind finding its way into his mouth. A plastic knife, a few grains of salt, a rubber scraper, some chopped parsley - look around for new props every few days.
It also helps to teach "hot" as one of a child's first words. This was wonderful for both my daughter and later my grandboy when they reached that "grab everything" stage. Sip a very warm, but not scalding cup, just barely within your son's reach. Warn him that it's HOT!!! and it could hurt if he touches it. Well, he will, and he'll pull his hand away (my grandson tried to wipe the "hot" off his fingers onto his shirt – very cute), and you can say the word again. Maybe touch the cup first yourself and pull away, exclaiming HOT!!!
This is a really easy, impressive, and harmless lesson for a child to learn, and an easy word for really young children to pronounce. Maybe repeat the lesson another time or two, if needed. Then you'll be able to warn him about what's hot. Even pre-verbal kids get it. (You will, of course, still need to be careful about keeping pan handles and other real hazards out of his reach for awhile. Little kids can get so eager to participate that they forget to be careful.)
If the high chair doesn't cut it, or wears thin after awhile, maybe daddy can play cooking games with your son. My son-in-law would set up a "kitchen" on a coffee table and start cooking with dry spaghetti and a big spoon in a pan. He'd have such obvious fun that my grandboy couldn't resist, and would head over there to help. Now that he's 2 1/2, he pulls a stool up to the stove and "helps" his mom. He's a little in the way, it's a little inconvenient, and it's just lovely to see him participating at the very heart of family activity. He can actually do a few tasks that are almost helpful. And he loves it. Who knows if this is how great chefs begin?
It's a stage, and an important one, I think. Your son is entering the great learning game of imitation. It's what little children do, what they need to do, what they are programmed to do. If you can find a way to allow him to participate in meal prep, you'll be able to gradually give him "real" tasks to "help" you. And eventually it will become helpful. Good luck.