It isn't their place to discipline your pets. Just as it isn't your place to comment on how they keep their home. It isn't anyone's place to walk into someone else's home and comment on pets' behaviour, children's behaviour or discipline (or lack thereof) or colour of the downstairs loo. Sure, it's anyone's place to think these things, but to act on them and actually begin trying to exert any power or control? Absolutely rude, rude, rude.
Of course, where danger is concerned (esp with pets/kids, but not exclusively), things are gonna be slightly different, but as a general rule, just no. Keep out of it. OP mentioned she had a handle on this already, it was quite unnecessary for anyone to "jump in" and use their own means of "discipline" at all.
Their house, their cats, their choices on how to deal with behaviour. End of.