I understand where you are coming from and agree that we need to know more about this to do it properly if required. However, I think some of this reflex is jusified by the known side-effects (not even the potential unintended consequences).

Greenhouse gases heat the surface and the atmosphere, but solar radiation management (SRM) mostly cools the surface. If you use SRM to get the surface temperature 'right' that atmoshpere is still warmer that it would have been. This means you get less rain. Many places care more about rain than temperature.

This is a well understood consequence, but the specifics are where it gets very tricky. There is a non-zero chance that using SRM to cool the planet may also kill the Amazon rainforest by reducing rainfall. This obviously makes things a whole lot worse and no longer buys us time. [0]

This is not even an unknown unintendend consquence, it is pretty clear already. Obviously this doesn't mean we shouldn't look into it, but we already know the consequences of geoengineering are ... not good.

[0] - https://acp.copernicus.org/articles/12/10887/2012/acp-12-108...