Twitching is common, nonspecific, and meaningless in the absence of muscle function failure which you have not described. Lots of people twitch. Up to 70% of healthy people have had or will have some sort of twitching. Your boyfriend’s twitching may be related to his back issues or not, but the overall picture doesn’t suggest ALS. In fact, widespread twitching actually points away from ALS.
It’s not always possible to treat twitching. Sometimes twitching improves with avoiding caffeine, stretching, massage, taking Magnesium Oxide supplement, and trying to manage stress.
Many doctors don’t recommend a back MRI unless there are localized findings on neurological exam such as abnormal reflexes or weakness that might suggest pinched nerve roots. This would be a good thing to discuss with his doctor.
EMG can show abnormalities for many reasons other than ALS. What your doctor ( and we) are saying is that the abnormalities on his EMG don’t fit the pattern of what is seen with ALS.