The issue is that Israel has no idea where those pagers were at the time of the attack, civilians were directly hurt by the explosions: https://www.pbs.org/newshour/world/survivors-of-israels-page...
You think you are not allowed to do a military strike if civilians may be hurt?
Zionists don't care about civilian casualties. It's extremely well documented. They even defend the explicit rape of their "prisoners". They will just explain them away as Hamas sympathizers and people will shrug their shoulders and move on.
Israel had in fact very clear intelligence that the specific pagers they were detonating were overwhelmingly going to be in the custody of combatants. This was very probably the most precisely targeted large-scale military strike of the last 100 years. That's not a value judgement; it's a descriptive claim.