Subjunctive "inevitable that" vs. indicative/infinitive "inevitable for"

Why does this require the subjunctive (because of the use of "that"):

"It was always inevitable that this virus become endemic"

whereas the following requires the indicative or the infinitive (because of the use of "for")?

"It was always inevitable for this virus to become endemic."

I would challenge the premise. Typically, the subjunctive follows phrases that are exhortative. "It is imperative that you come." "I suggest that he study for the exam." "It is essential that you be prepared." I'm not sure that "it is inevitable that" + subjunctive really makes sense. Even if it did, in modern English, many people would just use the indicative: "it is essential that you are prepared."

Honestly, in this particular example, I think the phrasing "it was always inevitable that this virus would become endemic" is much more natural than what you've suggested.