I don't know what Rod Wood or the Lions gained from that interview.
I think the Lions are generally in the right here. Signing bonuses come with conditions. It's not as if I could sign a contract with a company and receive a $5,000,000 bonus, then realize after three months I can just invest that money wisely and work as a minor league groundskeeper for the rest of my life, so I quit and pocket the bonus. The company is going to want at least a pro rated portion back, and I'm guessing that's detailed directly in the contract they signed.
Of course it's nuanced. Calvin and Barry you could have (and should have) worked with them on some PR agreements to keep them in the fold in exchange for them keeping their money. OTOH, Ragnow ostensibly left you high and dry in June.
Anzalone comes across as a lot of sour grapes about not getting the money he wanted last season. Yes, in my hypothetical above I'm typing at a computer for a company. You are putting your life on the line for a company. No doubt about it, they're not the same and you deserve immense respect. But at the end of the day, yep, you said it, "business is business." The contract says what the contract says. If you don't like it, negotiate the ability to retire whenever you want and keep your signing bonus. I bet you none of the 32 teams will agree to that, even if some of them have historically not sought repayment.
But back to my first point, why is this a story? Ragnow seemed perfectly happy fishing and hunting off into the sunset. He wasn't making public statements about the Lions wronging him. There was no Lions reputation to defend. I don't know why Rod Wood needs to make a public comment. "Our precedent goes all the way back to Barry Sanders. And if Barry Sanders paid back money... And I think the reality is, they're not paying back their money, they're returning our money. [Be]cause they were paid in advance for services that they hadn't completed."
Seriously, it's not even making a one-day story into a two-day story, it's making a zero-day story into a one-day story. He could have easily declined to comment on Ragnow's contract and wished him well in retirement.