The objection was to the idea that such people are "virtue signalling." It's such a silly and overused-term, generally used incorrectly, and used to snear at people doing good.
No, such people generally do think they are doing something worthwhile, and worthwhile things are right to do.
If, in fact, they are not doing anything worthwhile, which this graph suggests, then that is a mistake of the facts. It doesn't mean that they were just trying to "virtue signal."
From a climate-change only perspecitive, the original paper actually says that if you re-use a cotton bag just 53 times, you're already doing measurable good, and if you keep using it you keep doing more measurable good.
The higher number come from value judgements about other kids of impacts, and reasonable people can disagree over the relative values of those impacts vs climate change.
No, such people generally do think they are doing something worthwhile, and worthwhile things are right to do.
If, in fact, they are not doing anything worthwhile, which this graph suggests, then that is a mistake of the facts. It doesn't mean that they were just trying to "virtue signal."