Line 151 does this:
executor.schedule(this, 30L, TimeUnit.SECONDS);
so I'm guessing the problem that causes the exception is that the executor service has already been shut down by the time the VFS tries to clear the temp files. Of course, the real problem seems to be that that line of code is even reached, since it had to pass the delete check on line 149.
Since this doesn't seem to be an Arquillian-specific problem, I'm going to move this to the AS7 forum.