It really depends on the street, the traffic volume, whether it is a side street or a major highway... At any rate, and based on what you posted, "I" am just not feeling your reasoning there... But I have been wrong before.
Here's why.... Note that the citation you provided from the MUTCD states:
"When redirection of the road users’ normal path is required, they shall be directed from the normal path to a new path."
So if this was (say for example) a single block that was closed off, then then need for a detour might be a bit of a stretch... You ould have simply gone through to the next block, made a turn in the direction and found your way again.. It isn't really that complicated.
Also, keep in mind that just because other people made that same illegal turn does not, by any stretch, mean that you can follow them nor does it mean that it was a "trap"...
You're free to try it though... Good luck!

