It was a health and safety issue.
As long as the soldiers are there on offer, it's a personal liability for the core team if they run afoul, and not a new burden tot he state.
Everything boils down to insurance.
Just because there's an anomaly, it doesn't mean that there's a dinosaur. I'd be more worried about different pressure systems or under water 2 million bc flooding the shit out latter day London. Imagine the consequences if an anomaly opened just high enough up to be in space?