Recently, I wrote an answer to this question: When does a character cursed with lycanthropy become aware that they are cursed?
At the end of the answer, I pointed out that the character's alignment will only change if the character embraces the curse, as outlined in the sidebar in the Monster Manual, p. 207:
If the character embraces the curse, his or her alignment becomes the one defined for the lycanthrope.
However, on p. 206, it states:
By resisting the curse, a lycanthrope retains its normal alignment and personality while in humanoid form.
I interpreted this to mean that someone resisting the curse cannot voluntarily shapeshift. However, I could not point to anything to back this up, since it seems that, according to the sidebar, they simply gain the traits of a lycanthrope, which includes the Shapechanger trait.
Can a PC cursed with lycanthropy but who is choosing to resist the curse voluntarily shapeshift (i.e. use the Shapechanger trait)?
I say "voluntarily" just to exclude the "full moon" scenario; that's not what I'm asking about here.