On PLA Gen. Zhu ...
Enough emails.
Zhu is known for saying stuff like this. We have admirals and generals galore who make similar threats/blowhard statements toward China. When our guys do it, we all pooh-pooh it. When one of theirs does it (and says it's his personal opinion and doesn't rep official policy), then we get all jacked up ("Holy cow! The Chinese threaten nukes in a conventional war with U.S.! We'd never do anything like that!).
Of course, both sides, in their long-running MAD relationship, have made statements both suggesting first use and then denying such a policy could ever exist. This wordmanship on nukes is part and parcel of the MAD maintenance ("Insane I tell you! But, of course, we must consider ALL options!").
This is excitement only for those who forget their history. Calm down, I say. There is nothing new or threatening in this statement. Just the same-old, same-old.
Anyone, including Chinese generals, are allowed to blow smoke out their asses in public.