The principal question is, is there anything wrong with the grouting right now? Or to put it another way, would the bathroom floor, waterproof seal, tiles and grouting be OK if the renovation owners did nothing?
Obviously, there’s an aesthetic issue, but there’s also a question of potentially damaging the seal if the original grout is removed and new grout applied.
If I were on your committee, my advice would be to say no and let the owner pursue you to the Tribunal if they feel strongly enough.