I haven't checked Unifont but generally, zero with a slash has the slash only on the inside of the zero, whereas o with a slash, as you, being danish, know, but others might not, has the slash extending beyond each side. If Unifont has the slash going outside, then I agree with you, that is offensive, but if it does not, then it's fine.

zero with a dot in middle or very wide O narrow 0 (which is how proportional fonts deal with it) although unless it's quite exaggerated it's still not always obvious if you encounter one but not the other.

Some fonts have the slash through the zero is closer to horizontal and goes through just above to just below the x height. Orthographers can argue amongst themselves whether that is a distinct approach or just a variation of the /.