I dont really understand how a Dynamic Head would need a modesty layer.
Heads do not require a modesty layer, you can check the requirements for needing one in this link Marketplace Policy | Documentation - Roblox Creator Hub
If it really was taken down because of that I would submit a ticket, maybe it was actually another reason.
Now if it got taken down when you imported it to studio it could be due to the body you used. Roblox uses an automatic detection system for breaking the TOS on models, it might detect stuff as inappropiate, this could happen if you imported the head along with a “human looking” body and it got flagged.
If this was the case you could simply make the body less human or paint anything that isnt the head black.
(A modesty layer is just a part of the texture painted black)
Well seeing as it got taken down for “Sexual content: No modesty layer” It seems like you do need one. I could show you the warning message if you need more information.
Also, I JUST found out how to make the modesty layer (i think) as soon as you posted this basically. Thanks though!
I mean, if you showed the head (you don’t have to, if you don’t want to) maybe i could make a reason out of it. My only other good guess is that it could be violating any other TOS (too gory or something like that) or maybe some weird shading that makes a “Sexual” silhouette. Anyway i hope everything goes well for you!