Here, I’d say the point is the point at which they face legal consequences to what specific immediate end.
Harriet Tubman faced death as a consequence for directly freeing slaves, after suffering enslavement and terrible ongoing physical abuse that left her permanently brain damaged.
Greta taking things to the level of Civil Disobedience faces a slap on the wrist for the somewhat less impactful goal of delaying oil tankers for a while.
Greta is known for speaking loudly and publicly about climate change. Her level of effort and commitment is commendable, though I’m still not sure why she is held above the chorus of many many others saying the same stuff.
However elevating her to the level of people who faced literal torture and death seems to be a bit much, in some ways diminishing the efforts of those that did risk everything. I can see how some folks might roll their eyes when people start comparing efforts of protesters largely doing safe protests with low risk versus people who risked and sometimes gave everything for immediate dramatic result.