You are talking about the DSA.
There is no reason to believe that future social media bans will have such exceptions. VDL said explicitly that the app means that there are "no more excuses".
The DSA excludes small platforms from some rules, so as not to overwhelm start-ups with bureaucracy. Clearly, such considerations are to be neutralized in the future.
Good point. European governments keep churning out the digital regulation, but have hardly any qualified people to enforce them. That has protected the Fediverse, so far.
But a straight age-gating requirement would require no particular qualifications to spot. Would you be willing to face a hefty fine just for the privilege of running an instance?