At first thought, I’m thinking it’s a good idea to rotate the spare in...
1. Prolonged tread wear by some percentage... is it 5% or 20%?
2. Keep tabs on the condition of the spare.
But maybe some negatives as well...
1. Cost... additional sensor, sensor installation, tire balance to get started, then need to purchase a 5th tire when new tires are needed, mount and balance 5th tire.
2. Additional time/work when rotating.
I don’t know...
To me, the benefits of 1 and 2 outweighed the downside of the 1x cost for a sensor, sensor mount and ?balance, and the added time of the rotation.. There is the added cost of a 5th tire when you buy a new set, but you gain:
-a matching tire (assuming you change from the KO2's when you replace the tires)
-a fresher spare (opposed to a 1-?? year old spare) to get you out of a bind, and you can have full confidence in it
-depending on how long a set of tires lasts you, you probably should replace the spare with every other set anyway (just my opinion), so why not get some use (mileage) out of it and prolong the need to buy new sets a bit?
-if there ARE issues with it (balance, sidewall bulge, slow leak) you'll identify them that much sooner to get it taken care of.