Avengers: No "New" or "Junior" Avengers
You're afraid of this falling into the wrong hands and I get it, but this isn't like home. The serum isn't the only way of becoming enhanced. We have vampires and werewolves who are literally begging for the chance to turn someone. Just because Howard's the first to announce his serum doesn't mean he's the only one with it or the only one here who knows how to create it. We need the government to be on the same page with this if we really want to stop this.
And if you think we're going to just walk in there and take his stuff without a warrant and without fighting those kids, you're wrong. If we go through the law, we'll cover our bases and set an example for the other vigilantes that pop up.