Your suggested title is both vaguer and probably more wrong too: the thread claimed that cloud literally reflected the sunlight, causing less heat to go to the sea surface, there is no "masking" involved.

The current title is precise, the tweet chain is about sea surface temperature and the cause-effect of sulfur emission on the temperature. While it is related to global warming, and there might be other causes to sea surface warming as well, that is not what was discussed.

In terms of total global heat content sure. In terms of surface ocean temp, I'm not so sure you have a point. It's a pretty indirect path for greenhouse gasses to heat the ocean, and they can't push the water above the temp of their air.

Less shade however can cause solar heating well above air temperatures.

Your rewording is inaccurate. There is no masking, it was actually reflecting energy away from earth, reducing warming. This is important because, turns out, we unintentionally ran an ethically dubious climate engineering experiment, the results of which can now be used to inform future possible climate engineering efforts.