Syntactical and Idiomatic

[Brahman]

I was told in an answer to my previous question that the following sentence is ungrammatical:

1. The restaurant is pure vegetarian.

Could I say that in terms of syntax, it is right but the choice of word, perhaps, is wrong?

[Alan]

It is wrong grammatically because 'vegetarian' is a countable singular noun and therefore requires a determiner (a/the, etc.).
(N.B. Prefixed by an adjective, 'pure', it would have to be a noun rather than an adjective.)

However, even if a determiner were added, the sentence would still be absurd, since a vegetarian is a kind of person, not a kind of eating establishment!

I hope that answers your question.