I don't think their right or wrong to take the action they're taking, and some action is needed. I do think they're stupid though. Public support is key to growing a protest movement into something more substantial, and their actions will not build that.
The view of the general public on this issue (climate change) is very difficult to ascertain.... on the surface you'd imagine that nobody would disgree with the notion that as members of a species occupying a planet under threat, that individually and collectively we should be doing something about it, but even just reading the views on here, you can see it isn't the case.
The nuts and bolts of protest suggest that you need to get at about 3.5% of the population... the opinion formers, movers and shakers. Shift them and the rest flip overnight.
However that is very difficult.... as can be seen by the presence of a climate change denier in the White House and his lapdog soon to be PM of the UK.