That is just a test file, so let's not get hung up on the font choice OK?
You say it's possible, but offered no details on how to get it working. What's different? Do you have a sample ePub with working embedded fonts that validate? That way I could look at it and see what InDesign is doing differently.
I'm trying to figure out if InDesign is just doing something wacky, and if so, what do I need to do to fix it so I get the font working and validating. Beyond the question of can it work, I also want to know "how" to get it to work!