Who ended up building the centre?
Who ended up building the centre for kids who don't read too good? Mugatu was obviously sent to prison, and I am sure most of his assets were frozen... But even if his company had enough left to build the centre, for what reason would they do it? They don't owe anything to Zoolander. Yes, Mugatu promised to build it in exchange for him modelling on the Runway, but Mugatu is a liar. And I don't think the board of directors of Mugatu inc (assuming there is one) would be open to the idea of building a centre for the person who managed to get their CEO incarcerated (were these board of directors in the beginning of the film? I wonder).
My guess is, Zoolander managed to get the money from somewhere else, due to the renewed interest in him, he probably gained even more commercial success which allowed him to build the centre.