Once it is a security it is subject to all the regulations that govern securities. Most importantly, it would be regulated by American authorities (not Swiss as Facebook wanted) if any American used Libra.
I am sure that Facebook's Libra will be taking in this news as something they can still work with. Libra's people are all willing to work with the USA government just to be given the necessary approval to start the whole project. Strict regulations can in fact the best of Libra because we know that just like the government this is also a centralized entity and thus has to be subjected according to what that proposed law (of approved) do entails. And with this regulation in place, we might be seeing other players also coming to the market. Once Libra is approved in the USA market, it would be easier for it to penetrate the global market. Facebook has been a very regulated social media conglomerate so it is welcoming strict regulations with an open arms and even with a smile.