Surprisingly I was in Paris this year as well and... OK, jokes asides :-)
France is liberal place. No discussion here. Burqas ban is not changing that. In my opinion, context is important. Poland being Islamophobic, while France is not.
The point is the unusual tolerance found in the offbeat combination it is unusual for those strongly religiously traditionalist as those who wear burkas willingly to /not be bothered/ by something like same sex public displays of affection. Not being offended or leaving immediately at the sight or anything. The combination is fairly high entropy in an information theory sense.
It is certainly a sign of being liberal that one is allowed to wear whatever they like for any reason, and the state does not say, "Your religion is bad and you are oppressing yourself, and we are here to rescue you."
There have of course been illiberal but left-wing states that are willing to say exactly that. Most Communist governments have banned religion of any form on the grounds that the state knows better, but I don't think those governments are usually called "liberal."