I would usually be sad to see another original RPG go 5e compatible but Neuroshima was infamously poorly designed ruleset, possibly worse than Shadowrun. I probably won’t be running it, but may steal statblocks for my 5e game if I need weird stuff again.
Legally, they can’t keep you from publishing 5e content. You can even publish the 5e rules in their entirety so long as you change all the wording and pictures. I think they can keep you from publishing stuff involving their settings and characters, but you can still use their system.
Legally, they can’t send the Pinkertons to rob you, either.