Definitely looks like a crush injury to me. Can you tell whether there any feeling or blood-flow to the tail behind the injury? If there's no blood-flow the flesh will start necrotising and could spread. Are you prepared to cut away the end of the tail if it is dead to prevent any infection spreading? If the blood supply and nerves are destroyed I think the most likely scenario will be that the tail will whither and drop off of it's own accord, but a bit of minor surgery may be the best choice to avoid infection.
I hasten to add, that performing surgery on a snake isn't something I've ever done (the last thing I cut up was human), but with a medical sciences degree I'd be considering it.