>> I'm trying to ascertain their incentive here...

It's good for their mission and business.

1) Their stated mission is

"Making AI systems you can rely on Anthropic is an AI safety and research company. We build reliable, interpretable, and steerable AI systems" - https://www.anthropic.com/company

2) They've increased their credibility.

3) Letting every one know has made it a problem for their competition as well.