Maybe... If I was in their position I would want as many people on board from the get go as possible. When 3e came out, Green Ronin released the first OGL product at Gencon when the PHB was released if memory serves and I believe Creature Collection came out before the Monster Manual.
Yes, and maybe having other publishers jump the gun like that is something they'd prefer to avoid, given that the first Creature Catalog was widely regarded as not very good?
Making publishers wait on the license for 4e is what made Paizo go with Pathfinder
That's hardly an argument that has any relevance for this transition. Paizo had a choice to make, between OGL and an unknown license. No publisher is in that position now.