I mean I know hes a being of light now...
And he seems cool in the Thousand Year War audio books...
But he is a Nathrezim afterall. Is it just waiting for his time to betray us? I mean... look at how long Varimithras waited to betray Sylvanas.
Doesn't it also seem really odd that Nathrezim want to get close to the Windrunner sisters? It's almost like they want to shadow very prominent figures to have some influence.