Whether it's for the life of the garment or not, i don't know. Optimer certainly has marketed for the former, but i tend to be skeptical of corporation's claims, or rather their definitions--you might need a lawyer and textiles expert to fully understand the context and definitions they are basing it on...
For example, i like Polygiene's tech, and they boldly claim their NON wash in treatments last for the life of the garment, but if you dig deeper, it's actually rated for 100 washes. That's pretty dang durable (and impressive), but i bet you there will be some people that will use a garment longer and wash it more than that. An all polyester, or all nylon, shirt can last a good long time if designed well and not overly thin.
Now, bout the Merino, i can't say anything with any certainty, but on a trip my wife used a Dri Release polyester-cotton blend (15% cotton) baselayer, and i used the Paradox Dri Release polyester-Merino blend. Her shirt definitely had a bit more noticeable odor than mine, even though i had been previously constantly wearing mine for almost a week before, and she had just started to wear her baselayer the day before. She does not have unusual or strong body odor.
Was the difference due to the Merino vs the cotton, even though these are at small percentage? I can't say for certain, but it's certainly a possibility, especially since Dri Release yarns are usually designed with a synthetic core, wrapped on the outside by the absorbent natural or semi-natural minority fiber.
Hence, it's possible that having the Merino on the outside and the synthetic primarily on the inside, does maximize the efficiency of the small percentage of the former. Speculation though. I imagine without the oleoophobic coating on the synthetic though, it would get fairly stinky, though probably not as much as a 100% all untreated synthetic.
Either way, as you have noticed as well, it seems to be a pretty good combo, and at a great price.