Is this a "solo" only medical??

Nah, this isn't a "solo" only medical (there's no such thing) and more
than likely, it's an FAA screwup (seen it happen before). There are
certain conditions that don't disqualify you if you can get a SODA. If
you have a condition that will allow you to fly with a SODA but not
otherwise, you get a medical such as above, do your training, do you
solo flying, and when you take a checkride, you take it with the FAA
(some FSDO's may designate it, but not that I have ever heard of) and
you get your private and your SODA in one shot.

I guess it could be that he developed such a condition and was issued
this medical.

Michael