He's a Kennedy. Of course he speaks for all Democrats. No Democrat has come out publicly against his statements. Silence is assent.
Typically, rogues are disciplined in any functional organization, but those following the policy line are not smacked down. Kennedy fits the latter. Democrats do not view him as a rogue but one of the boys.
Oh yes. Please do. It's so important. I mean, it's not like we could find the same type of voter who votes Republican, right?
It is proof of nothing, unless you want to demonstrate that every single Democrat was a aware of Kennedy's statement and had some duty to report whether they agreed with it or not.
Silence is assent. No Democrats condemned Kennedy's words. We are not talking about people afraid to shoot off their mouths. By not condemning his words they tacitly support him.