Yes. Having a properly secured laptop on public wifi is no different than having a server on the public internet. It's not difficult to reason about the threat model here, and operating systems are fully capable of rejecting potentially harmful traffic.

You do.

> Do I need to explain risks using foreign local networks in HN ?

Do I really need to explain how not everyone knows everything?

HN is made up of many people with many different skill sets. While you might put emphasis and assign an ideal to the "Hacker" in Hacker News, you are ignoring the large audience of people here that come here from different backgrounds and offer different view points. You also ignore what knowledge people may or may not have. Not everyone understands network security where such things are obvious.

> I see it quite unfair to get a downvote for this.

Do I need to explain why complaining about unfairness of downvotes will get you downvotes?

Rather than whine about how smarter people than you might not know something you do, you could take the time to share knowledge rather than come off as a member of "r/iamverysmart".