I guess one could bring a laptop, spoof the Switch's WiFi MAC on the laptop and use it to login through that portal, and then disconnecting, and connect the "authorized" Switch. And make sure the Switch doesn't have "randomize MAC" like on Android/iOS.
Yep I've done it. What a pain. Thankfully now the Switch does have captive portal detect and a little purpose built web view for agreeing to the terms.
But that's a huge workaround for many.