I don't know what your experience is with "fusion" musicians, but I've been around them all of my life, and they're mostly jazz guys. There are players with little or no jazz training doing it (Dave Koz leaps to mind), but Dave Weckl isn't one of them. The players who invented the style were jazz guys. The music was a direct expansion on and extension of the modern jazz of the '60's. Despite Wynton Marsalis' partially successful campaign to limit use of the word jazz to music he approves of (plus the self-ghettoization by the LA/WAVE/smooth jazz guys), fusion has always been considered to be a form of jazz by nearly everyone else; most importantly by the majority of jazz musicians, educators, historians, and theoreticians. In fact it was the dominant form of jazz from roughly 1970-90. So this daylight you put between fusion and jazz is totally ahistorical.Sorry, not buying it. Weckl is not and never will be a jazz drummer. He has always been a fusion drummer, which is a totally different thing. There are those out there far more qualified to make judgements over the definition of 'jazz' than I am, but fusion developed in the 60's and 70's to be a distinct form separate from jazz. The aesthetic standpoint is different, the playing styles and techniques are different, the rhythms are different and the attitudes are different.
Dave Weckl could creditably cover any jazz gig in the world. That makes him a jazz musician. Whether you or I are wild about him aesthetically is irrelevant.
You're going to have a hard time convincing anyone who knows anything that Chick Corea is not a jazz musician. I guess he stopped being one when he was making the Return to Forever records, then suddenly became one again when he made the things with Roy Haynes and Miroslav, and was sort of partially one when he made Three Quartets or the Akoustic band record? That's not actually the way it works.Looked at his credits. Mainly Chick Corea and Mike Stern. Who are both fusion players. Corea was a jazz player, but also a key component in developing fusion into a distinct style of music that is not jazz.