I believe nudists carry towels with them when they go to restaurants, etc for hygiene reasons - and possibly to protect themselves also, imagine sitting on plastic seating - especially in hot weather.
Thing is, if they carry these towels around and visit a couple of establishments... do they, erm, sit on the same side of the towel each time, or turn it over to sit on a fresh bit putting the previously-used side on the seat! 🤢
I can understand walking around on a beach, in a field, on a nature trail, etc - and enjoying the fresh air feel on the body, but I cannot for the life of me see the point in carting around a towel in a back-pack with all the other things you need like wallets, credit cards, etc, just to go and sit squashed up at a table - indoors. And, if they have to go to the loo during the meal, they'll possibly be traipsing past your table which will be the same height as their bums - squeezing past it - yuk!
They seem like a couple of self-indulgent plonkers to me. And the pub, instead of boasting its 'inclusivity' credentials , should've asked the other diners / patrons if they minded... if they really want to be inclusive. They're plonkers, too.