Right/wrong.. well that'* tough to say. No where in the FSM does it say anything about threadlock. I have a few buddies that are/were dealership mechanics during the run of these motors and they say nothing about threadlock. What they do suggest is using a dab sealer on each bolt on the threads.
Here is a pic of what they recommend using
Thread locker may seal the threads from oil and coolant wicking up them. It'* not a sealant though, and I've yet to come across any LIM or UIM bolts that were ever loose and seemed to need it. As with anything there are a few different ways to go about it.
I learned about the sealant after noticing coolant puddling on my LIM not long after a gasket change. That was not long after partly following Bill Buttermore'* directions at that time.