Who's everyone during that time period?
Adam and Eve got old and pass away after Seth beget their great, great grandchildren.
If you think everyone is not malevolent you'll probably consider inviting all the criminals who were held in prison at your house. When I say this, you're shaking your nipples and urinating your pant by now.
Religious logic: The ant-eater isn't a threat to mankind. It's already inside the Ark among other animals.
Paleontologist logic: The ant-eater came after the late Cretaceous period when the previous dinosaurs died from ice age.