Using free/guest WiFi anywhere is a risky proposition. Better to use your own hotspot on your phone, cell service on your tablet/PC, etc. If you must use a guest WiFi access point, and do it often, you should invest in a VPN service.
Not only can the free WiFi networks be easily hacked, but many crooks will stand up their own router nearby with the SSID disguised as being for that site. For example, there have been many people connecting to fake WiFi routers in airports that look like airport-controlled devices. It's an easy way to "sniff" the network traffic and gather login and password information. They can also change the DNS settings on their router so your device gets the IP address of a spoofed website, fooling you into entering login info while they record it.
Blocking of gun sites is an inconvenience. Having your information stolen or a virus planted on your device is a real threat to your online security and finances.
The only time I use a public WiFi is when in range of a RoadRunner access point on Oahu. My phone plan includes unlimited data and free hotspot connections. I'll use that if I need to browse/connect an app using something besides my phone.