>>76929673Hal was basically an uncle to Wally and Wally did not like the idea of some guy who wasn't even "chosen" appropriately for the ring filling in Hal's place because he didn't think he earned it.
Remember, this comes from the perspective of a man who paid his dues to the superhero community for a decade before taking up The Flash costume when his mentor died. Kyle's just some lucky doofus who stumbled into Hal's gig so of course Wally's immediately hostile.
Eventually Wally becomes Kyle's best friend in the superhero community (though Wally's best friend will always be Dick, sorry Kyle).