M.F.
He's just experiementing. However, now is the time to nip it in the bud. If he's hungry, he'll eat and not play. You're doing the right thing to quit feeding him when he sprays his food, but I'd bump it up to the FIRST time. And say something like "No spitting. Dinner is over" or, if you want to give him a chance, say "You may eat nicely, or play on the floor." When he spits again say "That's so sad. You're not eating nicely. Dinner is over."
You might also try some finger foods if you haven't already. Both of mine were completely off baby food by about 9 months. Of course, then you'll e asking us what to do when he's throwing food across the table, or on the floor. The answers will be the same :-)
If he's the only one eating, just take him out of his high chair and clean up. If you're trying to have a family meal, put him in his crib or a playpen until you're finished eating.
This is the first of many meal-time battles to come! Just remember: You will never win a battle over food. You can't force a kid to eat. Put healthy, varied meals in front of him at regular intervals and let him eat (or not eat) what he will.