OP is @jacquesm here; this is the internet so long cons are always possible, but he's one of the more credible people around here. Additionally, the tweet in question is pretty far out of character.
No, it's a pun! As originally pointed out here:
https://news.ycombinator.com/item?id=31240589
the offending tweet was likely made as a reply (the @ match). The original tweet said "Some Russian soldiers say they are given a weapon and sent straight in. Learn on the job."
The pun was that Russian soldiers are not learning on the job, they are dying on the job. It's a completely normal observation to make.
The ellipsis at the end also indicate a pun/correction. An actual death wish would more likely end with exclamation points.
But the Twitter algorithms misinterpreted the pun as a death wish, and the OP somehow didn't remember making it. This sounds like the most likely explanation.