Fastfission wrote:
Less-practical but more in-the-spirit-of-it answer: Encourage him to release it under GFDL with the knowledge that nobody who really wants to make any money off of content is going to to be happy licensing their entire work under the GFDL and attaching all of its license agreements.
This seems reasonable; it really depends on what he means by "control of it". If he means control of licensing royalties, releasing it under the GFDL probably won't significantly impact that, because most commercial publishers would prefer to pay a fee than to comply with the GFDL. If he means control in other ways, then he would be releasing some control of it; for example, people could use it in derived works.
-Mark