As far as I know, It's impossible to prove a negative.
It's only a negative if it's not true, for anyone that has or even likely had a social media account and answered 'none' it would be a felony when they stated 'none'
What would be interesting is what a law like that would deem social media because under the basic definition even this website is a social media platform as is pretty much every forum on the Internet. To truthfully answer 'none' one would basically have to have remained offline and never joined any forum, message board, or big social media network ever. What about professional sites like Linkedin, that is basically a social media platform as well. Heck even playing online games that have messaging boards and player profiles could be deemed social media. Truth is social media isn't limited to just Facebook and a few other big platforms.
Your Android phone and even your iPhone for all intents mandate you sign up for services that include social media aspects to some degree.
It might be easy for some older people now to claim no social media accounts, but for younger people in the US it's going to be nearly impossible in the coming years to make that claim truthfully.