1 x chromosome match doesn't sound right to me, but I'm certainly no expert. I looked at my one-to-many matches and I have around 80. However most of them are in the 3 to 3.5 cM range so they may just be a coincidence and not real matches.

The person matching him on the x chromosome is most likely related to him through his mother. It might depend on how large the match is. If it's smaller than 5 cM then it could just be a coincidence. However just because he isn't matching anyone else on the x doesn't mean those matches are all through his father. Try googling something like "x chromosome inheritance" to read about it.