That's why I said "plausibly". From the TypeScript spec, it looks like it takes the Boolean grammar approach (treat it like a type expression if it's a valid type expression, otherwise don't):

The grammar ambiguity is resolved as follows: In a context where one possible interpretation of a sequence of tokens is an Arguments production, if the initial sequence of tokens forms a syntactically correct TypeArguments production and is followed by a '(' token, then the sequence of tokens is processed an Arguments production, and any other possible interpretation is discarded. Otherwise, the sequence of tokens is not considered an Arguments production.