Personally, I go with
Hanlon's Razor: "Never attribute to malice that which is adequately explained by stupidity." No need for elaborate conspiracy theories when simple incompetence likely covers it all.
But it must be disappointing for people who read about Carina's commitment to publisher DRM-free books, read about Kobo's commitment to offering DRM-free books if available from the publisher, then eagerly buyng and finding out that their books which were theoretically supposed to be DRM-free in both places aren't.
Kobo CS probably doesn't refund them, either.