I can put a flag on my own account. This should be disabled as before.
I opposed it, nothing but slanderous lies

A negative rating right now is completely useless and will be disregarded by the supermajority of the users (the same way that neutral ratings always have been). I'd actually advise against leaving them to save yourself the time and trouble; just skip straight into scammer flags.
That's unfortunate then. It still shows up right there on any board that displays it, just as visible. The only change there is that there isn't a trust score which I felt was less informative than a tally of all feedback left. I do think I'll still be leaving a healthy mix of them all, just going to be a while figuring out when to use what. I still like the idea of using the negatives because there is no guarantee that they'll be activated in a timely fashion, so it's a good back up.
This also means that the previous guideline for negative ratings is not valid anymore. You don't need to be scammed, not even close to that. You can, much more freely, leave negative ratings. It's all about those unconsidered side-effects.

This reminds me that the prime time to tag HostFat/Bcash/BSV with new flags.