I haven't looked it up but if I recall my definitions the FAA does not
consider an ultralight vehical to be an Aircraft. While It may meet
the definiation of a glider, if meets the definition of an ultralight
the FAA does not reconginize it as an aircraft and as a result it does
not need to be registered, Certified or require a Pilot Certificate to
fly it.


On the contrary, there is absolutely nothing in Part 103 saying that
an ultralight vehicle is not an aircraft. It is one, in accordance
with the definition of an Aircraft in 14 CFR Part 1.1.

Part 103 exempts ultralight vehicles from the requirements that would
otherwise apply to aircraft under 14 CFR. For example,
"Notwithstanding any other section pertaining to certification of
aircraft or their parts or equipment, ultralight vehicles and their
component parts and equipment are not required to meet the
airworthiness certification standards specified for aircraft or to
have certificates of airworthiness." Note that it does not suggest
that ultralight vehicles are not aircraft, it merely exempts them from
the standards and requirement for certificates of airworthiness.


It could be argued that as far as the regulations are
concerned there are no tow pilot requirements for towing ultralight
vehicals. As such a newly licensed recreational Pilot might be able
to
Tow ultralight vehicals with no endorsements required.


Again, on the contrary, 14 CFR 91.311 requires an exemption to use an
aircraft to tow anything other than a glider, and a glider can only be
towed subject to the relevant requirements.

It does seem to me that the FAA wanted to stay away from having
anything to do with ultralight vehicles, and probably didn't have in
mind the possibility that one might be towed by a certificated
aircraft. So certainly if substantial amounts of common sense aren't
applied by pilots themselves and people start towing hang gliders with
Pawnees, the FAA is likely to feel compelled to step in. Hang glider
pilots, in general, seem to have a fair understanding of what would
happen to a flexwing towed at 70 knots, and Pawnee pilots probably
have enough common sense not to try it, but then again to paraphrase
someone or other, no-one ever got rich by over-estimating the
intelligence of the public...

And Jim Phoenix is right: there IS a requirement that an Experimental
glider should have (Glider) in the Category/Designation block. The
reason, oddly, is to "ensure appropriate application of 14 CFR Part 61
.... concerning the medical requirements for the operation of such
aircraft."