It's naive to assume that someone working at the airport would actually know whats going on. These are the lowest level employees. They know what they need to know, i.e. "Take the bottle and throw it away". Maybe they give you some smoke screen story like "Ug there could be explosives in there. Or lord knows what."...

I am not sure, but to me it seems common sense that pouring potential explosives and poison into a bin, feels kinda shady...? No?

The real reason why they want you to dump all your stuff is simple. All these 45 million people need to rely on what the airport & planes provides. Lots of money to be made here...

A much bigger hazard: My MacBook with water damage. I am pretty sure the chances are higher that it just bursts into flames during a flight, than someone carrying explosives in a fucking water bottle.