That is most certainly hairloss. I hate to break it to you guys, but not all types of hairloss can be classified on the norwood scale. I just recently buzzed my hair and it now looks exactly like Tom's picture there. Diffuse thinning may not seem like much, but if he were to grow out his hair (like I did, before I buzzed it) it would become much more apparent as where the hair parts you would be able to see much more scalp than is normal for non hairloss folks.
Thems the rubs for diffuse thinners. In one way, we've got it better than others and in other ways we don't. We dont have to worry about hairlines which is nice though.