Of course France could do this.
And it is such a trivial thing I think they have a right to do it even if I think it is a stupid thing to do.
[Having said that, I do recall recently some high level political talks were cancelled because the Iranians were demanding that no wine be served. The French said "non" apparently]
I also disagree with Iran forcing women to wear ninja PJs.
Would I like Nazi Paikidze (hey, tricky name) to have the Chess tournament moved elsewhere?
Sure, fine with me. Make the political point. Ensure that Iranian women will not be able to participate to where ever the event is moved to etc etc over something that is nothing more than a trivial irritant.
I think women's rights in Iran would be better advanced by attending the event in Iran. Show that women belong at a chess tournament and make the point that forcing women to wear ninja PJs is stupid.
During her free time Nazi could get some pictures of herself without the head scarf on.
Then, once she is back home she could post those pictures to social media and show herself both as the competitor that she is and for her subtle ways at defying stupidity.
I think that would be more effective for all involved but that's just my opinion.