Because the background "movement" that the killers are said to have belonged to was fringe.
From our perspective, there's a monolithic "Tea Party" composed of people that are all alike with all the same views. This is, of course, a bit of derangement because there are various Tea Party groups within what was a larger movement with a fairly wide range of views on some topics. (It's rather like saying the "left" is a monolithic movement, from the Socialist Workers Party to left-leaning Democrats. Which, of course, the rightmost 5% or so of American society fervently and honestly believes, and is a like kind of derangement. When your group boundaries are made of 5 ft thick titanium alloy and 50 meters high, it's hard to have a clear view of the other side.)
In any event, the fringiness made the connection difficult.
The recent protests weren't fringy. Having as one's foes "police" and "cops" and even "pigs" and decrying the entirety of the police force as oppressive, militarization of American society, etc., etc., wasn't all that fringy. Or, if it was fringy, it was popular among a rather large contingent of Americans.
The symbols of the protests were also invoked as the motivation for the killings. Explicitly.
So while the attitudes may be similar and in some ways mirror-image, the mainstreamness of the parts of the movements involved isn't.
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