Yes! I don't think your boys feathers are light enough to be a "Blue Grey" (which I imagine is possible, although not sure I've seen it) so he'd be a "Black" underneath all of the genes that add the pretty silvers and markings : D It's hard to say honestly what that chick could have grown up to be, Lavender, Splash, White, and some blues (and I think some paints as well?) can be pretty light as chicks.
Most Blues are gonna be darker cause thats what most standards want, and while its technically possible that chick could have been a blue, I find it pretty unlikely. It's a little late here and my brains a little mush but if I remember correctly the light coloured chick who passed was from the Grey x White birds, right? I think its more likely that chick was white or perhaps even a paint than it was a very light blue or a splash, I'd expect more of a darker hue to the back.
My Splash cochin Miko (rip) was the "lightest splash I've ever seen". I got her as a chick and he was picture perfect for what you'd assume a splash bird would look like. We even got a white chick in that same batch and she looked totally different. Well for her entire life Miko never had more than 6 coloured feathers on her whole body xD Never bred her though, but she was a lovely bird <3
If/When you breed your Grey & White again I'd love to see what they make