Like some others, I initially engaged this individual, and then decided to back off when I could see that it was pointless.
I'm in the school of thought that, it's probably best just to ignore altogether.
For myself, I have nobody on 'Ignore', but if I would choose to do so, I use "manual ignore". It's called the scroll wheel.
I do 'thumb down' threads to close them and put them out of my sight.
Having said all of the above, I do still occasionally view a thread, just because I want to, but stay silent.