I see it. Very general. Is there anywhere that he says in these cases the subject is first?
The linguistic rule from Buth works regardless of article or word order. And he gives a grammatical reason why based on clauses coordinated with και.
I honestly don't blame anyone for a misunderstanding here. Having reread Wallace's remarks now, I do find them somewhat ambiguous on their own. The heading "articular nouns and proper names seem to have equal priority" might be understood to relate to each other (an articular noun with a proper name, with or without the article) or distinct from each other (articular nouns have equal priority with other articular nouns or proper names have equal priority with other proper names).
However, when you look at the examples he gives, it seems clear that he includes pairs of articular nouns that aren't proper names.
Mt. 6:22
Ὁ λύχνος τοῦ σώματός ἐστιν ὁ ὀφθαλμός. ἐὰν οὖν ᾖ ὁ ὀφθαλμός σου ἁπλοῦς, ὅλον τὸ σῶμά σου φωτεινὸν ἔσται·
(But, I don't think this example demonstrates his point well.)
I John 2:7 Ἀγαπητοί, οὐκ ἐντολὴν καινὴν γράφω ὑμῖν ἀλλ’ ἐντολὴν παλαιὰν ἣν εἴχετε ἀπ’ ἀρχῆς·
ἡ ἐντολὴ ἡ παλαιά ἐστιν ὁ λόγος ὃν ἠκούσατε.