Maintaining this as optional is not providing any tangible benefits but has real costs to developer overhead. So, these normalizations will just always be enabled.
Two steps to be taken,
Remove the flag from the code (I5de9e42ab0dd36a751c19e06dc42403bd7c7ada7)- Now that we're always guaranteed to be serializing from a normalized form, we can eliminate some of the wikitext escaping that proves impossible to generate.
A third step could be to get clients to stop passing the flag, as a cleanup.