Regarding Hal Ostrander’s five reasons to oppose a young Earth: Yikes!
I’ll only address his first point. Today’s Tigris and Euphrates rivers are not claimed by any young-Earth leader or organization to be the original rivers of Eden. Rather, of course, they are named after those rivers, which Genesis makes clear would have been destroyed in the flood.
Consider Connecticut as a modern example. Including the couple of towns that prefix the word “new,” New London and New Britain, the state of Connecticut has about 60 cities and towns named after places in the United Kingdom, including Hartford, Danbury and Greenwich.
That’s what people do when settling new lands. They name things to remind them of familiar places.