I'm not a fan of SRM, but this isn't true.

The idea people in the SRM research community have go more like that you have declining CO2 emissions, at some point you turn around by deploying negative emissions tech and SRM is basically your "let's cut off the worst effects in times of highest CO2 concentrations". This is e.g. often described by David Keith, who's one of the leading advocates for SRM research.

Whether any of that is feasible or realistic is of course debatable, also whether one should even go down that path and whether even the prospect of doing SRM is blocking faster climate action. (And I sympathize with all those concerns, but I think paiting a wrong picture doesn't help.)