I never really understood Badspot's hateboner against suggestions made to let the admin control who gets to save his build.
It would be a nice feature to have in my opinion.
This situation is similar to if ever LEGO set designer ever didn't want to release a manual for their creation because people could, "steal it". There's no question of who created it at all because there's no transaction of goods or credit for OP's build unless Badspot adds it to the default saves list. I can understand people being sensitive about having credit taken for their art, but in this case this guy is obviously making empty threats and isn't going to make a formidable attempt at having people think he created OP's build.
I can't guarantee this, but if I had to estimate I'd say 25% of the time when people save builds, it's to look at the build in greater detail to help them build better. About 74% of the time is probably people backing up their builds or saving their work (ignoring autosaver-created save files for obvious reasons), and at less than 1% of the time is people saving builds so that they can take credit for it and host it on their own server.
Here's another way to think of it, if people's paintings were never showcased in Museums but kept in bank vaults, they would never be stolen. But then absolutely nobody would be able to appreciate them or be inspired by the painting. The vast majority of people going to a museum don't want to steal the artwork, just like in Blockland. It does happen though, just not very often.
It's a pros vs cons situation and the pros ridiculously outweigh the cons.