there is no safety issue in flying at night with observing Fi
Probably not, but once qualified, the pilot can then exercise the privileges at Night solo, even if his visual acuity is such that he can't see a thing. The medical restriction that causes this problem is surely there for Safety.
The old UK system of permitting an IR with a No Night safety restriction got around the problem without compromising the medical safety issue. The Dutch approach fudges the whole thing and could leave the Authority negligent.