http://www.signandsight.com/features/588.html
Last summer it was made known that Bluitgen was having trouble finding an illustrator for his most recent book project: the life of the prophet Mohammed, told for children. Islam forbids representations of the prophet, but Denmark is a secular country and Bluitgen had the best of intentions. Nonetheless, the illustrators he approached were wary and turned him down. The murder of the Islam-critical film maker Theo van Gogh by an Islamic fundamentalist had shaken up the Danish arts scene. (news story)
If this version is true, he didn´t try to keep the names secret, he didn´t find any who were willing to do it. Out of fear.