Very true. I only said mildly dangerous, as it will work without issue almost always. It's the almost that gets me, and since I very rarely shut down, it makes sense to watch the process to ensure my system is still well behaved.
Others have higher risk tolerance, I prefer to keep an eye on things and not assume all is well until I've verified it to be so.
That has not been advertised as well as it should. Occasionally people should time the array stop, and use that information to customize their shutdown time to suit.
Can the array start and stop timing be readily harvested from log files? If so, I think it would be useful to keep a separate saved list similar to parity check statistics, that way you could look back in the history to find how long it generally took the array to start and stop.
Also, a notation that the previous shutdown was unclean BECAUSE of an elapsed timer and not a hard crash would be useful, especially in the OP's case. If the timer kills the array, it should notify you.