Sounds like a tricky situation imo, I wouldnt take the risk to get myself in that position.

I don’t see the point in remixing someone’s track for own personal experience. Its harder to come up with your own shit and you learn a lot more. However I could relate to it if it was a track where you thought you could improve on it and remixed it for your own enjoyment but to do that effectively you need the single hits and sounds/synth patches tho. That would be good!! I think its very disrespectful releasing a remix without permission of the original person who made it and the least you can do is contact them and inform them of your situation. If someone did that to me I would have to listen to remix and see what’s changed and more importantly what’s not. If there was something in there I like, new angle of approach I would let them go and release it, at the end of the day we are all supposed to be fighting the same battle?
Releasing it without permission is plain disrespectful imo, esp if its a remix of something and has certain elements hooks n grooves that made the original what it was. Thats where you consider sending in the heavies