There are several angles to managing global warming, and directly targeting managing the composition of the atmosphere looks like a good approach.

Especially given that this is how we caused the problem in the first place, but personally I favor also tackling managing climate via controlling incident solar radiation by using fleets of thin-film mirror satellites that can vary their orientation to the earth. This way they could change the size of their cast shadows and also the target of their reflection.

Assuming the ability to modulate a few percent of the incoming solar radiation we should be able to have a significant control on one of the main forces driving climate.

With modeling and experimentation I expect that by using this (coupled with CO2 reduction and significant engineering to mitigate glacier erosion) we could end up avoiding a lot of the ravages of runaway climate change.

So, this is what Musk talked about when he spoke about giving $100M for carbon removal. It's clever. With a bit of luck a multiple of this amount will be invested by other people while participating in the race to win the price.

Edit: it looks like I was out of the loop. He tweeted that himself when announcing the amount: https://twitter.com/elonmusk/status/1352392678177034242