I do not have the Bushnell Legend M but do have the Zeiss SF 10X42 and it is tack sharp. I was using it last weekend looking at a drake Mallard about 20 yards away in the late afternoon winter sun and the view was spectacular. Every bit of detail of the feathers stood out. There was nothing lacking in the view.
I just did a hand held braced print comparison (looking at a printed target) between the SF 10X42, a Nikon EDG-II 10X42, a Zen-Ray ED3 10X43 (possible "M" clone) and a Vanguard Endeavor EDII 10X42. The SF, Nikon and Zen-Ray all appear to resolve past my acuity level which I estimate to be about 20/15. The apparent sharpness of the SF seemed slightly better than the EDG, but that is most likely due to the more neutral color balance of the SF. The Endeavor EDII was not as sharp as the others and that is puzzling considering the several reviews mentioning that the new EDII is very sharp. I am still trying to figure this out but I am suspecting it may need to go back to Vanguard to get checked out.
Now to answer your question if the Outdoor Life comments on resolution have validity. In my opinion, No, Nada, Nein and Zilch. The area of expertise for them is firearms and ammunition. I would give them much more credibility on their opinions of how a firearm operates or the ballistic performance of a round but not so much on optics, especially binoculars.
There is no telling how careful they were in their testing. As you know, if the diopter setting is off just a little bit, it will be noticeable in lack of sharpness. Did the tester take the time to set the diopter multiple times to make sure the setting was consistent? Who knows! Did the same person test each of the binoculars at the same time under the same conditions? Who knows! Where the lenses pristine? Who knows! Without knowing more about the tester and details of the testing process, there is no telling what took place and what can be concluded from the results.
I live in a hunting state and have a bunch of hunters as friends and acquaintances. Many are extremely knowledgeable about hunting, firearms and ballistics, but none are that knowledgeable about optics. They are mainly influenced by advertising, what the pros uses and what hunting buddies have. I would not be surprised if it is similar with the Outdoor Life staff.
My own experience with the SF is completely contrary to their conclusion. I have looked through 8 or more SF binoculars now and have not seen a lack of sharpness in any of them.
I guess they could of obtained a bad sample of the SF but that is unlikely. Most likely, they screwed up the test, probably with an incorrect diopter setting. As mentioned, optics is not their forte.
The Porters did a test of the SF and scored them a max of 10 on resolution. The Porter's test is not perfect but I put much more faith in their conclusions on optics than I would Outdoor Life. Optics is not a sideline with them.
http://www.birdwatching.com/optics/2015_titans/chart_2015.html
The resolution tests I immediately consider valid are those done my some of our members, especially David/Typo, Steve/Moreorless and Steve from KY. For any other comments, I consider the source and the context of the comments.
There are many reasons to question the validity of the Outdoor Life resolution results. I put about as much faith in it as I would most Amazon binocular reviews.
The Bushnell Legend Ultra HD has multiple comments on this forum of the plastic diopter ring failing and some units having focus issues, mostly right out of the box. Maybe that is what you are thinking of. There is not much out there yet on the new Legend M and I have not seen any reports of these problems. The only focus complaint I have read is one that had some free play. If you come across some reports of the M having these issues, please remember to come back and post a link.