Is the rogue source extant?
Yes -- but ...
ISTR that rogue only came as a binary, there was no source.
That was true at first, certainly the original binary was passed around. It might have been an early net.noise pass around, but ISTR for Tektronix on V7 I got the binary from someone at UCB directly -- Mark Bales, maybe, who was a UCB doing a summer Internship and he may have brought them with him.
The sources were later released as part of a CSRG release in the post 4.2 timeframe ??reno/tahoe I think??, but by then the binary for the Vax was pretty popular and the sources had begun to sneak out - as I know I had them at Masscomp and Sun had them too. Paul Cantrell (of video teco fame) created a color version of it and IIRC may have added some other graphics when running on a Masscomp tube.