I can't remember where I read it now but I read that Meyer had to give the ok/assent but that Chicago handled the contract. There was some tension between Chicago and Siegel over the proper sharing of Trans-America wire service and Chicago was eager to avenge the slight. I don't know if this was the case or not.

"When the snows fall and the white winds blow, the lone wolf dies but the pack survives."
Winter is Coming

Now this is the Law of the Jungle—as old and as true as the sky; And the wolf that shall keep it may prosper, but the wolf that shall break it must die.
As the creeper that girdles the tree-trunk, the Law runneth forward and back; For the strength of the Pack is the Wolf, and the strength of the Wolf is the Pack.