From their terms of service:

They (private repos) are also allowed for really small & personal stuff like your journal, config files, ideas or notes, but explicitly not as a personal cloud or media storage.

I’d guess that most private git repositories are small enough to fall under this category (unless you track large non-text files in git). This also seems like a very reasonable policy, considering that they’re a non-profit and they want to focus on supporting open source projects.

Honestly, instead of trying to remove Snap from Ubuntu, I’d just install another distro (PopOS for example is mostly like Ubuntu but with Flatpak instead of Snap)