A happy update: Today, the 19th, Bean (short for bean blossom) took a sunflower seed I was holding out with my fingertips.
How I've been handling him is that I've been just standing by the aquarium when I saw that he was out, and after about a minute dropping a sunflower seed from high up, and then standing there another minute and slowly leaving. He's seemed less and less afraid, so this morning after 2 seeds I lowered one into the tank in my fingertips and he snatched it! He didn't go immediately to his burrow, but he did soon after.
Still don't know if he's a robo, but he has no stripe in the middle of his back. I looked at some robos in a pet store and he seems larger than that, but then, the pet store lady said he was the larger of the two in the enclosure when I bought him. A large robo? Even if so, after this morning, this being only day 9, I'm thinking he's going to turn out to be a pretty calm pet eventually.
The idea that he might be a robo and need extra patience was helpful and well worth the price of being on this forum.
{there wasn't a price}