I am not against the move, but there are many things to consider.
I think Walt wins this battle no matter what Dusty does to sabotage it. Chapman is a supreme asset if his value is made out properly. Walt has vision and understands the way an organization maximizes that value long term.
Jeff Samardzija, Chris Sale and Lance Lynn were all successfully transitioned from the bullpen to the starting rotation in 2012. Samardzija threw 174.2 innings. Sale tossed 192 innings. Lynn hurled 176 innings. I expect to see Chapman treated similarly.
I used to defend Hal and his opinions, but man, he's gone wacko. If you get the Sunday DDN, he spent over half of his "Ask Hal" article defending the keep-Chapman-in-the-bullpen belief.