I don’t have much to add I’m afraid. First time seeing them as well. If they had some kind of release, it was an extremely small one at maybe one event. Pretty unlikely, but not impossible based on some other one-off releases/leaks I’ve seen. Although if he got them from a Pokémon Exec (by which I guess you meant staff member at some event?), I think they might be unreleased cards that weren’t supposed to be given. 
Either way, thanks for sharing and asking here. Always cool to learn about new cards that exist, even if we don’t know why they were made or how they were released yet (or leaked). Happens more after than one might think tbh… Take this other recent thread for example (Cross-Hatch Holo Call of Legends Lost World; Lost Remover; and Twins); or this thread (unreleased Japanese BW-P Emolga; Druddigon; Pokémon Catcher; and 4x Energy tournament participation prizes); or this (now deleted and only visible to mods 
) thread (Pokémon League stamped Drakloak); etc.
Sometimes more copies emerge eventually when people realize they exist after a few years and search for them specifically, or people who own them realize they’re worth a lot (e.g. the Japanese unlimited E1 cards; no-bar Kyogre/Groudon ex cards; non-shifted Glossy Keiji Kinebuchi Pikachu; etc.). But sometimes they might remain the only copies to exist for many years.
Anyway, I’ve never seen them before. And whether it was an intentional release or accidental leak, they’re defintely rare either way.
Greetz,
Quuador