Comment by briHass

What are the similar arguments?

Firearms are capable of being used for legal purposes, as they are in the overwhelming number of cases. A radio that transmits on a restricted frequency is illegal. The ruling doesn't say legal frequency transmitters can't be sold, just that the broker (ebay) is responsible for ensuring it's not facilitating the sale of illegal radio equipment. Ebay is the one choosing not to sell most radio equipment (even if legal), because they don't want to deal with it.

Firearms used to be widely available at big-box stores, as they were legal (and still are), provided the store prevented illegal purchases. Most box stores/locations no longer sell firearms, because they don't want to deal with it.