A significant number of attendees of the "420 event" were attendees of the former Extinction Rebellion event therefore the hypocrisy stinks.
JC, you seem determined to call this hypocrisy, now by lumping all these folks together. There's a climate problem, and while we individually may not appreciate these efforts, we are certainly big enough to ask 'what am I doing about climate change?', aren't we? The answer for the vast majority of readers here is likely not much. This while noting that the RS demographic is a large consumer/user of modern aircraft, which are part of the climate problem.
Overall I'm a bit shocked by the seeming nonchalance of many here to a problem they are a part of, in favor of being annoyed at some hippies who are trying to actually do something about it.
From the Snopes link, which debunks the notion that they left a bunch of garbage behind when protesting an environmental concern:
The image on the right is at least a year old and comes from Versova beach in Mumbai, India. It appears that this image was circulated in a bad-faith attempt to paint global-warming protesters in a negative light.
The image on the left truly shows rubbish in Hyde Park. However, the image was taken in the aftermath of a celebration for 420, a marijuana-centric holiday, not a global-warming protest.