Please pick something else to take a stand with. A child that needs to be held should not be denied that time no matter if he can talk or not. His need for that is greater than your need for him to use words.
Think about it, he might have felt filled up with your strength after being held and been able to blurt it all out. He "might" have even been able to be healed of this tribulation. Needing to be comforted and loved physically (nurtured) is a basic humane need. Not something to be held back.
Now on the other hand, if he wants to watch TV, play a video game, use the computer to play a game, etc...those are trivial things that he could be denied if he couldn't ask for.
I would not make him use words for food or comfort or other basic needs. Other stuff? Heck yes, he'd be needing to use his words. He'd still get most of it but there would be a time for him to try and speak.
You have a lot of good advice in the other answers too. I did some research in college with children's drawings. It could be that you need to go check out some books through the local library. Read them and see if you can get him to do some drawings. Just normal playtime side by side time. Draw pictures yourself and let him draw what he wants.
For instance, if the child draws a family picture you can look for certain things to see if someone is abusing him. Things to look for would be vacant eyes, gnarly teeth on an adult while the other adults have normal mouths, huge feet or hands totally out of proportion and the others are normal, there are ALL sorts of clues in a child's drawings/art. I learned to much.
Be goofy, draw pictures of your school days alongside him doing the same thing. Start it out like this perhaps.
"I had such a fun day today, I got to do some fun stuff at the park with you. I reminds me of when I was in school....I know what, lets make/color some pictures!!!! I'll draw me outside playing on the playground when "I" was in school and you draw a picture of you outside playing on your playground!!!! Won't that be fun to see?". Making it totally about something fun and then ignoring the rest of what happens while you're drawing is the way to go. Draw like a child would draw. Better than stick figures if you can so you can have facial features and stuff. But his artwork could be a huge window into his mind.
There are so many other ways to get through this block without him realizing it. I do suggest a good therapist too. One that does play therapy and will teach you to do PCIT, parent child interaction therapy. We learned it for free through the local county health department. We are a low income family though. They offer many things that normal people have no idea. Call yours and find out what services they offer to kids.