I really don't think there is anything to worry about. OSHD used copyrighted content to develop off of. The runelite plugin has been confirmed to use no assets.
The biggest problem with most OSHD clients was the technology behind it, not the assets. Hell, if it had worked we would have used it. Sadly the OSHD code was not up to scratch for a commercial company and making it so would have meant opening hooks into the code which could've been exploited by bots.
I think the OSHD client mentioned below tripped a whole lot of bot detection systems so would not have been workable either.
This may well be different, will be good to see where it goes.