The boring answer is that Mossad probably were the ones who convinced Hezbollah to move to pagers in the first place, likely through double agents, and likely also controlled the supply chain from the beginning. They probably also didn’t actually care about who specifically had a pager, and just made sure they were distributed thoroughly within Hezbollah.
They’re already arming themselves for a civil war and openly calling themselves domestic terrorists, and your response is tea? You’re naive if you think neighborliness is enough to avoid the coming conflict, they’ve already killed Americans.