He absolutely does not need meat. So that's one worry to scratch off the list! :)
Seriously. According to the American Dietetic Association, "appropriately planned vegetarian diets are healthful, nutritionally adequate and provide health benefits in the prevention and treatment of certain diseases.... Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood and adolescence. Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer." (http://www.eatright.org/cps/rde/xchg/ada/hs.xsl/advocacy_...)
Ok, so, that waxed a little long, but I really want you to not have to worry about whether he's eating meat.
The pureeing idea is sheer genius. Try it again, but just start with very small amounts. Very, very gradually, puree more and more, and reduce the "cheese" sauce as you go.
Oh, and I really encourage you to nix the hot dogs. They have lots of extremely creepy stuff in them. Puree, like, beans. Cooked chard. Broccoli. Things like that.
Or, just "run out" or the mac and cheese. Whoops. While he might refuse any alternative offering for a meal or two, no kid will starve in the face of food (they really won't!). I know it takes some courage on the part of Mom, but let him go hungry for a day or two (or, heck, three). He won't, even. He's still getting his snacks, and they're healthy, and he's still getting plenty of stuff to drink, so, have no fear!
For lots of kids, snacking is their primary food source, anyway. So, yeah. You're doing great by giving him super healthy snacks. If you do the gradual-puree route, also consider giving him smaller helpings. Again, gradually. When he's still hungry, or comes to you later being hungry, offer him a healthy snack or "dessert" (try squashicles! Puree some baked delicata aka "sweet potato" squash - the kind that looks like fat cucumber - and stick it into some popsicle molds. It's delicious! Tovolo makes some very cute BPA-free plastic molds; you can find more at Natural Family Living Blog, http://www.naturemoms.com/blog/2008/07/04/cool-off-with-h...)
You can, as you see on this web page, make all kinds of fruit-veggie smoothies and give those to him, as well as turning them into popsicles and fruit-veggie leathers (remember Fruit Roll Ups? These are way, way better). Get yourself a food dehydrator and have fun. It really is fun. Get him involved, as they always say. It really does work. And what kid doesn't like goo? :)
Keep in mind that it takes several tries of a new food to get it to "take" - so don't consider one or two or 10 thumbs-downs as a no-go for him. It's a survival thing: we all reject, out of hand, any food that we can't relate to any other, more familiar, safer, food or flavor. It's a way to safeguard us from poisoning. after several tastes, over time, we see that it isn't making us feel sick, so we start to like it. So keep offering, don't give up!
L.