I dunno why people are questioning this. Maybe OP is like me and doesn't feel comfortable with leaving his server unmoderated.
I used to host a freebuild and did it all the time
Sure, a
couple times I got on and it was spammed
But the vast majority of times was nothing but a few undeleted weapon/vehicle spawns
Not worth blocking everyone from playing on it
And that's a freebuild, something like a DM would be even less risk
Blockland is the only game I've seen where people are obsessed with administration
A better idea would be to fix the things that you would need to be kicking people over, ex:
not use an add-on that breaks spam protection
and a way to easily contact admins in case of an issue.