Short story I disagree with the negative feedback at this point. I completely understand why you feel the need to leave but I feel it's premature, and the reference doesn't support it, yet.
The user can be clearly seen to show in 2 posts that they state they do not recommend anyone buy the product. Each of the posts has a last edited time stamp of the Feb 11 and 12th respectively by Frodocooper, which predates your negative.
I look at it this way, is there a chance this member has actually tried to buy the miner and is then trying to defend his countries name, maybe. I've seen people go apeshit over how great their country is so that doesn't generally throw up any flags for me. People who might have been scammed and find a group pointing it out tend to go on the defensive first, no one likes being a sucker.
In the end all i'm saying is there is reasonable doubt. The member didn't actually start the topic, it's likely only still open as OP was banned for plagiarism if i'm not mistaken for this very topic unfortunately.
Just a small note in general, I think you should be as willing to paint green as red, or go neutral for possible red as you would for possible green.
Try to shore up references with all feedback, including risked BTC as that gives the feedback weight to anyone looking beyond the score under the avatar.
Good luck with your DT journey.