Ivermectin is VERY safe if overdosed. I have had an experience in the past when a foal got the WHOLE TUBE in error (full sized horse foal). The vet said not to worry, it was quite safe, and he sure wont have any worms! They have also tested it in other ways- letting it sit in a hot car for months, then testing the contents, etc... not that I would recommend that, but was told it passed with flying colors.
Just edited to note though, that I agree, I dont like the 'suggestion' of the article!! Then what?!!