Len,
Maybe it's just me, but it seems fitting for the Dad on the Moms Panel to respond to a guy asking to run in a Princess Half Marathon! ;-) Can you guess my answer? :-)
If you are up for it, and don't mind being in the minority (OK...you might be alone), I say go for it!
Just to be sure it's OK, I went through all of the registration pages on the
Princess Half Marathon web site, and there were no rules against men, and I was not prevented from registering despite the fact that I was registered as a male.
Having said all of this, it certainly appears that the spirit of this run is not seeking male participation. For example, this is the race description:
"The [race] will bring women of all ages together to participate in a magical event designed just for them. The Disney Princesses are the inspiration for the weekend’s events and will focus on the attributes every princess possesses: commitment, courage, determination, fantasy, perseverance, and strength. Every woman is a princess, which princess are you?" Also, one of the registration questions asked is "Who is your favorite Disney Princess." If any of this makes you uncomfortable, I'd advise skipping this run. However, if it makes you think about purchasing an aerodynamic tiara, then this might be the perfect race for you.
Lastly, please be aware that you may have to surrender your man card during the race. I've been there, and it isn't pretty. I'm hoping to get mine back real soon. ;-)
Good luck, bro, making your final decision.