On the air - with ease.
In looking around last night I got to this page. Evidently I wasn't the only one with the dhcpcd not being shut down issue. The problem was fixed in a later revision.
I grabbed the latest official release and after checking that I didn't make any changes, I put the new wifi-radar main file where the old one was (after renaming the old one, so I could go back to it if needed). I still saw the errors, but it does shut down dhcpcd properly and thus also connect again without my having to fiddle around.
The curious thing is that I am now running revision 72 rather than 43... but the fix I noticed was in revision 86. Scrolling down, a similar issue was taken care of in revision 71. Evidently I got lucky and only ran into the earlier bug.
It looks like I'll probably be putting Wolvix on the laptop after all.