No where did it say that the MOC had to be based on a form that Makuta has taken before. And look at these other entries:
That demon face is cool and Makuta never had one like that
When did Makuta look like this
Or like this
Lego is encouraging people to be creative. The dragon head is nice looking and well built so I don't see the problem.
Edit Plus Makuta has had so many different forms in the 2 gens(not including the brotherhood) And he was a shapeshifter in G1 so he could literally look like anything.