How do actions such as this promote the cause of those who performed them? I can't think of anything more self-defeating. There are, in general, four ways to achieve an end. The first is to use force. The second is to use coercion (i.e., the threat of harm). The third is to use manipulation (e.g., deception). The fourth is to use rational persuasion. Only the fourth is respectful of persons, which is a moral imperative. I would argue, from a consequentialist point of view, that only change brought about in the fourth way has any chance of long-term success. The first three means generate resentment, alienation, and backlash. Many people who accept the ends reject the means. Eventually, they come to identify the end with the means and reject the end itself. When that happens, what has been accomplished? Precisely nothing. Indeed, things are worse at that point than they were at the outset.
Everyone who cares about the environment must emphatically denounce these actions. Everyone who cares about animals must emphatically denounce (as well as renounce) the use of force, coercion, or manipulation to improve the lot of animals. I hate it when someone refuses to denounce extremists. When someone from PETA, for example, refuses to denounce those who use violent means to pursue their ends, it links PETA with those means. Why would someone even hesitate to denounce those who use violent means, other than misplaced solidarity? I am not in solidarity with thugs. Anyone who cares about the environment or about animals will be judicious in the selection of means, and will not hesitate to condemn those who use inappropriate means. How often does it have to be said that the end does not justify the means?