[ApK]

Just sticking my nose in to offer that Kindle support and financial reasons are not the only possible factors for switching back.
Perhaps a lot of patrons simply hated the new system and complained, for reasons unrelated to Kindle.

Also, just my gut feeling, I think a lot more than 5% of their ereader users are on Kindle.
If the 5% of "digital downloads" is not simply incorrect, then it maybe referring to 5% of ALL digital downloads, including movies and music and audiobooks.

So even if only 5% of all their downloads were for Kindles, that could still mean even less was for other ereaders, and all the rest was other media.