Summer and Winter have Queens yes.. but that does not need to imply that ONLY Queens can rule. There have to be Kings somewhere (and not just the Erl-King either). I remember from a lot of the enumberable books on Fey and Faerie that there were Kings. Oberon was often away, and the Queen had a lot of power (I see them as Oberon/Spring and Titania/Summer). I'm looking at this as a power play by the Queens to usurp a good bit of power and weaken a potential rival at the same time.
I plan to use Oberon as the King of Spring and I think that King is better for the aspect. It is the planting season, the Farmer tills the land. Summer is more the nurturing and caring of the crop. I'm thinking of using Mabon as the Autumn King as Mabon was listed in many tales as a mighty Hunter, a harvester if you will. Mab would be more life in suspension, awaiting the coming of Spring.
My current thought is that Oberon had gone missing some time ago and Titania took over as much of his power as she could, Mab unwilling to allow her rival to create such a significant change in the balance of power had to do likewise to Mabon. I see Mabon being either a prisoner in the Winter areas of the Nevernever or possibly in hiding. Oberon is simply wandering about either in our realm far from caring about the intrigues of court. The courts of Spring and Autumn decided not to go head to head without their Kings and keep quiet and out of the line of fire until one or both of the Kings return.
This seem like a reasonable idea?