Personally, I'm not vegan, but feel compelled at this stage to defend it anyway.
The two main reasons I hear for veganism are:
1. Producing animal products exposes animals to suffering and exploits them (at least if it is done in a "mass market" way).
2. Environmentally, eating animal products is unsustainable for our current and projected world population.
I think both are valid reasons. And they are also potentially valid reasons for protests that affect other people and businesses.
So I'm going to reframe the question: If a validly constituted business is built largely or entirely on exploitation or represents an existential threat to humanity, is it valid to disrupt that business? My answer would be Yes, it is valid (though I wouldn't necessarily disrupt that business...). Even some actions that are technically criminal, such as trespassing, could be morally valid.
I'm not convinced that the vegan activism described actually meets that criteria, but I'm fairly sure some of the activists involved do think it meets the criteria. And I think that's where the debate gets particularly messy, because yes, it is personal opinion whether the criteria is met, but in an inter-connected world our choices affect those round us and vice versa, and it is valid to consider those effects and try to raise awareness about them. I don't know how to balance these considerations.