I think what he's missing is that he's approaching the question of "how do I make these people care?" from a liberal position. It just seems like such a weird question to even ask someone who cares about others by default.

If you think of it from the perspective of a self-centred conservative though, you can ask the question as "how can I frame the pain of others as their problem?"

Try talking about solutions in a way that affects them personally:

• You want transit and bike lanes 'cause nothing reduces traffic other than viable alternatives to driving. Get those other people off the road so you can drive.
• You want to stop sending weapons to Israel because we're spending your money on weapons for their war.
• You want to divest from fossil fuels because renewables have better energy security. Your costs don't go up whenever those people start a war over there.
• You want high taxes on the rich because they're festering parasites sleeping on a pile of gold and we want to spend that money on the poor so they aren't so desperate that they steal your shit.

These people do not (cannot?) care about how many children are killed by our bombs or about the fate of some bird, so constantly appealing to emotional arguments meant for liberals will never work on them.

I always thought it was a distortion even to put the two on a level as right and left wings, as if they're equally valid alternative views that balance each other. One starts with an understanding of the basic truth that we share this world and must support each other, and tries to work out, with intelligence and care, how to arrange things so that everyone can thrive. The other is a roiling mess of ignorance, hatred, narrow-mindedness, greed, and personality disorders. To frame it as if there's an ongoing debate of left vs right is no more valid than to say there's an ongoing debate between astrophysicists and flat-earthers, medical researchers and antivaxers, or climate scientists and climate change deniers. Funnily enough, all the absurdly ignorant, time-wasting positions on the right-hand side of those pairs are actually popular among the right wing. Conservatism is a personal limitation (even when it's also a grift), not a real political philosophy.