I don’t know of it it was related, the dates suggest not as Heroes World was bought in 1994 and the Image move was 1996 when they had nearly collapsed. Jim Lee invited him to move the book to Homage because he was a fan. I remember Moore writing later he just preferred doing it himself.
I think it was the case with Bone it was earlier and the reason given was to retain its place in catalogues.
Scholastic have their own kind of unique way of working. They effectively license specific editions to sell primarily through their book clubs but also in shops, so all the time they have been selling Bone, Smith has also been selling it through Cartoon Books in different editions. As far as I know they are the only company that does that as usually a publishing deal means exclusive rights.
It has sold bucketloads though as you say. I bought a copy for my nice a good 8 years or so back and it boasted over 3 million copies sold on the cover.