how so? nowhere does it actually say either way...

here

Where are the Farie kings?
Yes they do.  The Erlking as sort of the Hunter king, and Santa Clause, the Winter king who is not the commercial Santa Clause.  The kings are sort of the opposite of the queens in their given season.  They are independent of their Queen’s courts.  The Erlking is not a particularly friendly guy, whereas Santa Clause is kinder, the spirit of generosity in a time of bleakness.  Yah I’ve gota have Harry ask Mab about him so she can roll her eyes.

  Actually, the modern myth of Santa is just a reinterpretation of a character known in many Germanic traditions (Someone else mentioned one of them Zwarte Piet "Black Peter"), who around midwinter would travel the world giving gifts to good children and savagely punishing (usually beating or kidnapping) naughty children.

Actually, Zwart Piet is one of a number of companions of Saint Nicholas/Sinterklaas. See also Belsnickel, Knecht Ruprecht, Krampus, Le Père Fouettard, Grýla (and her husband, big black Yule Cat, and 13 Yule lads). Some slightly less (overtly) terrifying companions include Mrs. Clause and Snegurochka.

As for overt Santa analogues you've got Joulupukki, Père Noël, and Ded Moroz among others, while the giant Olentzero, and old woman Befana are slightly more interesting anologues for being noticably different.

   So the "real" Santa would probably be more like this (as infact the real life santa was, until he was Disneyfide into the Santa we know).
  What it said in Summer Knight was that in times of great imbalance, the Wyld fae could be "called", basically drafted for the war, but even in those circumstances, they got to choose which side they fought for (also choosing a side would be necessary since no fae would be safe from the war). Now yes, the nasty Fae usually chose Winter, and the nicer Fae Summer, but that was just a rule of thumb, not a compulsion.
   In the end, each wyldfae chose for itself whether to fight and who to fight for. This is proven by the dewdrop fairies choosing to side with the Pizzalord.

Actually, some of the Wyldfae chose and some were overtly abducted- it varied.