First, you've completely mischaracterized Obama's position. It's not as simple as, "Think of the children!" Obama is saying that encryption makes it practically impossible to prosecute some kinds of criminals. Of the examples he listed, one of them was child pornographers. Another was plotting terrorists. Now these examples are trotted out all the time, but that doesn't make them false. Robust encryption protects everyone's privacy, but it also means that some number of child pornographers and terrorists will get away with their crimes. Obama thinks the harms of those crimes outweigh the privacy protections. I don't agree with that, but it's not an unreasonable view to hold. And it's certainly not the view you claimed Obama had.
Second, it's absurd to think –even for a second– that Obama doesn't care about the lives of children in Iraq or Afghanistan or Syria or Libya. If coalition forces didn't care about innocents, they would have waged war like the Putin did in Chechnya: indiscriminate bombings, extrajudicial killings, and record-setting deployments of landmines. But that's not how coalition forces operate. The horrific stories you hear about are accidents, not deliberate. Due to incomplete information, poor decision-making, or just plain bad luck, soldiers sometimes kill innocents. When this happens, everyone agrees it's a tragedy, and everyone tries to prevent it from happening in the future. Sadly, militaries are incredibly blunt tools. The only way to completely avoid collateral damage is to never use them.
To make my point absolutely clear: In the case of drone strikes, children die because intel isn't always accurate and weapons aren't perfectly discriminating. Despite what you're trying to imply, if Obama could wage war with perfect intel and weaponry, he wouldn't harm a single innocent person.[1]
Lately, I've been seeing more of these drive-by misrepresentations on HN. I usually downvote and move on, but the situation only seems to be getting worse. I don't know of a good solution, as any reply takes far longer to write than three sentences of pandering.
1. A side note: The same can't be said for the leaders of the opposing forces (Abu Bakr al-Baghdadi and Ayman al-Zawahiri). They would use these hypothetical perfect weapons and intel to turn much of the world into a charnel house.