GoogleFrog wanted to remove names that were holdovers from Total Annihilation. Archangel wasn't in Original TA, but was used as a name by a few third-party unit creators: https://units.tauniverse.com/?p=q&q=archangel
- Accordingly, it wasn't on the "must change" list, but as the unit renames were being discussed, someone felt it could use a rename if a good name could be found.
I think GoogleFrog in particular liked "Toad" because it jumps.
I argued for Skyscraper (originally suggested by someone else, but I can't find that post any longer) as a clever double-meaning semi-joke in the vein of the other Jumpfac units Firewalker, Placeholder, and Moderator. Firewalker is a unit that walks around and shoots fire, but a firewalker is also a person who walks over hot coals as a stunt. Placeholder holds units in place, but a placeholder is also a thing that you put in place temporarily until you can replace it with something better, thus jokingly suggesting that the unit's name is a temporary name until we can find a better one (which of course makes it the perfect name that will never be replaced). Moderator slows units down, which is also one definition of "to moderate", but a moderator is also a person on a forum who edits and removes forum posts to prevent flamewars, and of course Zero-K notably has an active forum that requires moderators. So in that same vein, a skyscraper is a very tall building, but the Skyscraper unit also scrapes aircraft out of the sky.
But, alas, GoogleFrog liked Toad better, so Toad it is.