Any line of thinking, taken to its extreme, is counter-productive at best, evil at worst. "Be thoughtful about where you spend your time and money" is not exactly a slippery slope we should be worried about.
The author admits at the end of the article that they aren’t absolute in their boycotts and that it’s hard to fully boycott certain things that are so prevalent within our lives.
It’s not that deep. Just be more mindful about what you do and what you use to do them, and you’ll find better ways to do them down the road that will make you and the people around you happier.
So don't take it to its extreme. Just put the effort in to make good choices up to the point it's more personally disruptive than you can handle.
Person A: I try to avoid eating beef regularly, cattle farms are so environmentally unfriendly.
Person B: Taken to its extreme, we should eliminate all cattle. Say goodbye to the hamburger!!!
Um, it's possible to walk and chew gum at the same time.
While you’re at it, you should make your own clothes, grow your own food, and build your own home with materials you procured sustainably.
Taken to its extreme, this line of thinking is such a non-starter that I don’t even really know what to do with it.