I can not give a clinical diagnosis on the internet without seeing your husband or his test results.
If he has
weaknessWeakness in his arms, then this is less likely to be associated with benign fasciculation syndrome (this disorder is real but does not have muscle weakness or wasting, and the fasciculations are more widespread from the onset).
Several conditions can cause muscle weakness and fasciculations - pinched nerves or nerve roots, ALS, multifocal motor neuropathy (less so), some inflammatory diseases, some viral infections of the spinal cord (eg West Nile and others). Stability of symptoms for a whole year would not be typical of ALS.
Multifocal motor neuropathy is diagnosed by nerve conduction studies and clinical presentation - the antibody tests are a supportive finding - so I do not know what other evidence your husband has of MMM. This is a condition that can look like ALS, but the nerve tests and antibody tests should tell the difference.
Good luck