[SilasX]

It sounds like you're saying you don't know how bad X is relative to other things, and nobody can make an estimate, but it's definitely not infinity, and the possibility of X favors your preferred policy over others.

That doesn't sound like it justifies any one tradeoff over another, nor tell us how we should decide to.

[specialist]

What's your best estimate for cleaning up the Great Pacific Garbage Patch?

You've heard of the precautionary principle?