Terrorism implies violence or threats of violence. Neither Greenpeace nor Chris Eaton can be reasonably labeled as “terrorist” or connected with terrorist actions. Calling such organizations and people terrorist is disrespectful to victims of actual terrorists.
It can be argued that eco-activism hurts “the economy”. But that argument goes both ways: Some practices like whaling, mining, fracking and deforestation do (or can do) massive ecologic damage, and are not sustainable.
Just because some people have committed violence in the name of defending the environment, why does that relate to greenpeace. As far as I know they are are non-violent.
This is what is wrong with the label terrorist - it mixes up people happy to shoot at crowds and bomb markets with all sorts of other people the government finds threatening. The aim of its use is to label people as beyond the pale and therefore not worthy of the protection of our laws. We should be very wary when this label is used.
That these powers have been abused for detaining and searching members of greenpeace, or film makers like Poitras, is a very persuasive argument for me that the government should not have these powers of arbitrary arrest or detention at all.
And the problem the law has with it is not due to it's ends, but with it's means.