Not that it's bad. For me, it's actually very useful, I just find it mildly amusing that an app for managing AppImages is packaged as a Flatpak, despite the two formats being widely known as competitors*.
* Okay, most people (including me) would say that the two formats are for different use cases and aren't directly competitors, but for the eyes of a lot of AppImage purists and Flatpak critics, they are.
Speaking of that app, I have been using it for some of my programs that are only available as an AppImage for sometime now and I can confirm it works really great.
obviously good for the bit, but the serious reason why this exists is likely because it's a modern gtk app -> it's meant for gnome users / made by a gnome users -> gnome is all in on freedesktop/flathub -> these users can all expect to have flatpak availability as a common method of distribution -> therefore, release it as a flatpak, so these users who already have flatpak can more easily manage their appimage-only programs