This seemed completely ordinary to me, and less archaic and unusual
than "cleave to" which I would never say, whereas I would use "hew

A quick google search shows entries in Encarta as well as the American
Heritage Dictionary.

I don't have the OED handy, but I don't think it's a new usage.

Apparently the AHD classifies phrasal verbs like this as intransitive,
even though the preposition is obligatory and the object must be
specified. While I understand the analysis, it would seem more natural
to me to see "hew to" as transitive, but with a funny preposition,
just as one might have a verb that governs the case of its object in a
case-marking language.

Still, I suppose that any analysis of English phrasal verbs is going to
be weird in some ways.

   -- David