Huh. I'm noticing that offline the admin at least has creative always on even if unticked. I disabled offline admin and unticked creative mode inventory and with a new character (name) still had CM on. It's as tho the offline server direct from the menu ignored that setting and defaults to on. Which makes sense since few play offline in survival mode.
I'm gonna try something else I'll report back on it later.
Edit: In three easy steps you can survival mode like the pros.
Goto your SM folder usually something like C:\Program Files (x86)\Steam\steamapps\common\StarMade\
First look for admins.txt and put some random crap on the first line so there's no risk of someone accidentally becoming admin. Or you can add one name you want to have admin power. But there has to be at least ONE entry in that text file. Any other admin names go on separate lines.
You'll then need to run starmade-launcher from the same directory. In the launcher (NOT THE MENU) use the Dedicated Server feature and press Launch. An unskinned (white, old style UI) Java window should pop up and load your default universe (which ever you set it to). Leave that window open.
Now re-use the same starmade-launcher and use the Play StarMade option and press Launch. Goto online mode and add this server: 127.0.0.1:4242
Join your local host server as any name not previously used. That new name should not have admin or creative_mode at all.