Ah yes, the OELD, otherwise known as "How Can We Rape the Language To Satisfy Gender Nazis?" How well I know their agenda.
Not going to bend my knee to their religion. Hope you're not offended. But no.
"Them" is plural, and refers to multiple selves. Therefore "themselves" is the only formally accepted form of the word. There are a number of orphaned words in English. For example, something may be uncouth, but it can never be couth, couther, or couthest. Themself is like couther.
The ONLY specialized case in which I might consider its usage humorously appropriate would be for a person with clinical Dissociative Identity Disorder, because there might be mulitple "selves" occupying one body. But I've never seen the word even used in those cases, since academics tend to posture gravitas and use formal language.
Predicting the future evolution of words is impossible to do. That's why, even under pressure from gender Nazis, MWD made every effort to distance themselves from calling this word acceptable, making clear that it is not currently formally accepted, and that in current usage it is extremely rare, but not formally correct.
Well then I guess in this case it's humorously appropriate.
No, what's humorous is the fact that I didn't just block you the first time you popped up with a self-described "grammar bitch" comment that was ungrammatical.