There are numerous complex issues here in the philosophy of so-called animal cognition or comparative ethology, but it seems to me that the burden of proof is with anyone who says no. The same issue arises, clearly, for human beings. So if we say that we do not know that the beagle feels love when he wags his tail and bays a bit and licks us and even gives us little nips behind the ears, and is obviously happy - more than happy - to see us, and delights in our presence, why would we not say the same about the human being doing these things, or their non-beagle equivalents? It's no good saying that he's doing it because we feed him. The same is true in the human case, but the manner of feeding is different, as is what is fed. It is difficult to imagine an ant loving us, but I think that is because there is no demonstration of affection from ants, no licking or running round in circles and so on. They would be ignoring us, if they were human and doing what they do. None of this is an assumption, though; it seems to be more of a common sense observation, but one that ignores false philosophical paths.
The claim that something "symbolically supports tyranny..." is not a claim about the act in itself, but a claim about the meaning of the act. Your vegan friend may see troublesome meanings in the act of eating artifical bacon flavored chips or wearing fake fur. But not everyone does, and there is much ambiguity and complexity about what things mean. To take another example, I have friends who will not marry because they think that "marrying symbolically supports an institution that oppresses women." I don't doubt that marriage has historically oppressed women, but I think marriage has multiple meanings (commitment, family, for example) and any decision whether to marry or not needs to take all these meanings into account. Back to the fake fur: Personally I prefer fake fur that looks fake, so that I don't make unnecessary enemies or set a bad example. Your friend is so passionate about veganism that he focuses on one set of meanings.