Some of this sounds pretty typical of a quirky kid to me. If a kid is never forced out of his digital comfort zone, he doesn't have the social practice that's necessary to not be awkward in this area. I suspect that more and more kiddos will be behaving this way. I am a MS teacher and even the most "mature" kids have a lot of trouble communicating in an articulate way because they simply never have to.
One of "my" parents was telling me how her daughter, soon to be 16 and driving, had NO idea of the street names and locations of things in her neighborhood. She's an extremely bright girl, but her mom noticed that once she got her phone (insert PSP, etc here) she completely stopped making conversation in the car and being aware of her surroundings. She was in text-land CONSTANTLY.
No kid is talented in everything and almost all of them are very ego-centric. Some MS kids are seriously clueless. I swear, my first year was spent asking myself "what's wrong with these kids?!" - HA! You have to approach everything as a teaching situation rather than be concerned that they don't just know how to behave or communicate.
I recently read an intriguing article that speculated that the ridiculously high rate of autism could be attributed (among other things of course) to parents today having a real lack of experience with kids and therefore the wide range that constitutes "normal". I think there may be something to this. So many parents are so paranoid about their kids that they drag them to one specialist or another demanding to know "is this normal?" There is a VERY wide range of "normal" in human beings.
Some of this - esp the retreat into the games, etc - could be his chosen route of escaping the pain of his parents' divorce / not being w/mom, etc. If everyone is just "letting him be" and not engaging him in discussion about his feelings, etc, he may just not be the type to put them out there.
Honestly, I'm kind of with your husband. An alarming number of kids out there are emotionally and socially crippled due to a myriad of issues that aren't always autism. I suppose an evaluation couldn't hurt, but I think I would try these other things first:
-Lay down ground rules for screen time (none at dinner, car, etc)
-Teach that making conversation is part of good manners and he is expected to participate with the family. Mumbling is rude and lazy (unless you know he is physically not capable of speaking clearly).
-Model good manners and conversation / articulation for him in your day to day interactions. In a non-threatening, kind way, encourage him toward eye contact when he is speaking with you. Note if he becomes agitated by this. Most kids are a little uncomfortable with it, but does he shut down?
-When things happen, engage in family conversation about the events and encourage the kids to talk through how they feel. Confirm that you are there for them and love them very much.
-When you're trying to get answers to questions, lead him to the possible responses to focus him- much as you would a toddler
If these measures are tried for a month or so and you're observing that he is not able to come around and adjust to them, I think an eval might be in order. Have patience - don't just leap for the "easy way out". Invest in him and try to get to the root of the issues by eliminating or limiting some of the barriers.
Without being a fly on the wall in your home, it is impossible to know what other factors are coming into play here, but I hope this is helpful.