Agreed. The reason I stuck with the simpler question is because you need to move your audience from A to B, not A to C. If you get them to B, then I think that can also get them to C, as that question can be applied to whatever reaction they have to the author’s preference. If they think “it’s true that the author prefers to promote his books at Dragoncon, and so he’ll never get value out of my convention,” they can respond “is that true?”. (Your question is a more targeted version of that.)
Agreed. The reason I stuck with the simpler question is because you need to move your audience from A to B, not A to C. If you get them to B, then I think that can also get them to C, as that question can be applied to whatever reaction they have to the author’s preference. If they think “it’s true that the author prefers to promote his books at Dragoncon, and so he’ll never get value out of my convention,” they can respond “is that true?”. (Your question is a more targeted version of that.)