Perhaps a less-brittle version would be to replace "we don't know X" with "we can't easily prove X to the extent needed to deter it."
We dont need to prove it to deter it.
If in doubt, treat it as a bad writing and give that feedback. It is a bad writing.
We dont need to prove it to deter it.
If in doubt, treat it as a bad writing and give that feedback. It is a bad writing.