No i mean that Mark Gurman from 9to5mac has sources that Apple plans to take place an Event at Moscone center in the week of the 14th March. And mostly, the Keynote happens on a Tuesday. This leads to the 15th of march 2016 were a reservation was taken.... The GDC does not take place inside the Moscone Center.. So the Keynote from Apple could be happen paralell to the GDC.
Where are you getting that Mark Gurman said the event will be at Moscone Center? The location of the event is not described in anything I've read from him. He only describes the date.
Source:
http://9to5mac.com/2016/01/22/apple...arch-with-new-bands-os-full-redesign-in-fall/
Also, what makes you say that the GDC does not take place inside the Moscone Center? The GDC has Moscone North, South, and West all reserved from March 14-18. Not only is it taking place inside there, it's taking up the entire facility.
Source:
http://www.moscone.com/site/do/event/list?nav.type=0&nav.base=1601&nav.filter=1603
Apple is not beholden to use the Moscone Center for its media events. It has its own on-campus facility which it has used in the past.