Why would it be? The only problem I think there might be, is copyright laws, but, if a remix is released by legitimate means, it’s perfectly legal. The reason I bring up copyright laws, is that because unless a law is unjust, we’re required to follow it, and breaking a just law is a sin. Keep in mind, also, if someone’s not making money off of the copyright, then it’s a little bit less of a problem. If I wanted to put a video on YouTube, and credited the original artist, but didn’t monetize it, that would be perfectly fine. If you want to, I would refer you to Tom’s diner by Suzanne Vega, given that it’s the remixed version that’s more popular, and the people that remixed the song, did not ask her for permission, however, they did have permission before it was released, but not before it was recorded
