Hi,
There's a number of places these npcs can be getting loot from.
The grenades, guns, rocket launchers could be coming from the default Rust loot but that seems unlikely.
Make sure your kits don't contain these items by mistake. Also check and see if you have any other plugins which might be giving loot to npcs,
such as AlphaLoot.
If you want to use CustomLoot for BotSpawn npcs then, yes, you need to set "enabled": true in your second snippet.
You would also need to customise a loot table, though. The "default" loottable is a placeholder and has everything set to 0 so, unmodified, does nothing.
Either modify the default.json file to your taste, or change to "lootTable": "SomeOtherNameHere" and reload CustomLoot.
That will give you a new file - SomeOtherNameHere.json - to work with.
That's how new loottables/files are created - Just enter a new name for "lootTable" for some entry in config, and reload CustomLoot.
If one loottable for all of BotSpawn is enough then that's all you need.
However, if you want different BotSpawn profiles to have different loottables, there is a global option in CustomLoot config to enable that.
Set it to true and reload.