Why is it bogus? People who choose not to consume or wear non-animal products*, still seem to be perfectly fine with not avoiding animal products in other parts of their lives.
If you mean by "People who choose not to consume or wear non-animal products" vegans - because vegans choose not to consume or wear animal products - you are making a huge personal leap assuming vegans are "perfectly fine" with not avoiding them in other parts of their lives. Again, you are demanding that before anyone dare argue with your "eat meat so it won't be wasted, and buy second hand leather and fur so it won't be wasted, and still call yourself vegan" stance, they must be living in a cave, with no clothes, no store bought food, no electricity, no means of transportation except their own feet, etc. Just because I, for example, live in a rural area with no bus service, and the nearest place of employment is 47 miles away, must drive a car to have a job, doesn't mean that I am either perfectly happy with this, or that I have no right to call you out on the idea that vegans who refuse to eat wasted meat are not really vegan.
Why should their lifestyle get a free pass when they criticize those who seek to reduce the environmental harm that comes from manufacturing by not embracing the consumer culture in the west and instead reusing old clothing?
You can go ahead and criticize vegans all you like. My own idea of what justifies making criticism is that I remain willing to be criticized. I don't need to be perfect, or better than anyone else, in order to criticize what they have to say. All I need is to be willing to take it in turn.
But what you shouldn't be doing, and what I believe most people here are arguing against, is trying to change the definition of veganism to suit your argument. Veganism and environmentalism are very different ideologies. There is very little overlap between them. When it comes to a question of whether to directly benefit from the exploitation of an animal, or "harm" the environment by refusing to benefit from said exploitation, the vegan chooses to avoid benefiting from the exploitation. I don't think anyone in here is saying it is superior morally. They are just trying to make choices that are most in line with veganism.
What you are trying to do is claim veganism encompasses every aspect of environmentalism, so you can accuse vegans who are not environmentailsts of not being vegan enough to criticize you for thinking vegans should eat meat that will otherwise be wasted, or buy second hand leather or fur for environmental reasons. That's what's bogus.