I also lean heavily towards it not being Moe Howard.
One thing that might change my mind is if Moe ever made any reference to having worked with John Bunny on Film! As Mr. Bunny was considered to be the first cinematic star (He was also the first to be the cover story of a major magazine directly as a result of his death, which occurred in 1915!), I highly doubt that Moe wouldn't have referenced this, at some point!
As a child actor, Moe worked at Vitagraph and did indeed work with John Bunny at least once. This surviving film is not
one of those times.
LITTLE NEMO (1911) is not a new discovery, as some are claiming on FB group pages. It's one of the few Vitagraph comedies that survived the decades, and it circulated for many years in deteriorated condition. It was restored in the early 2000s (or earlier), and elected to the Library of Congress' National Film Registry in 2009.
Film experts, especially Vitagraph historian and John Bunny documentary producer Tony Susnick who has spent years researching all extant Vitagraph documentation, have indicated it is not Moe Howard. And of course there is the obvious evidence that the boy in the film has little-to-zero resemblence to Moe.
Between a bogus IMDb credit submitted by person 'unknown,' Amazon extracting/compounding bad IMDb data for DVD reseller listings, and uninformed fan comments at Youtube and similar video-hosting sites... the misinformation spreads.