I wasted many minutes on this, but I'm pretty sure that yes, he can. Creative commons is just a boilerplate to get you started in an actual litigation, not itself binding (especially not their FAQ page). If he only displays his comics with these captions, anyone who ignores them will now very likely be liable under french law.
AFAICT the only thing that could possibly change this is if he explicitly passed his "moral rights" to another person, but obviously that doesn't apply here. CC-BY 4.0 contains this clause, but I don't think you can just be made to "agree to waive" these rights, as "to the extent possible" hints at:
Moral rights, such as the right of integrity, are not licensed under this Public License, nor are publicity, privacy, and/or other similar personality rights; however, to the extent possible, the Licensor waives and/or agrees not to assert any such rights held by the Licensor to the limited extent necessary to allow You to exercise the Licensed Rights, but not otherwise.
AFAICT the only thing that could possibly change this is if he explicitly passed his "moral rights" to another person, but obviously that doesn't apply here. CC-BY 4.0 contains this clause, but I don't think you can just be made to "agree to waive" these rights, as "to the extent possible" hints at:
https://creativecommons.org/licenses/by/4.0/legalcode.en