I'm reasonably sure they will hybridize, but why would you want to produce a mutt that might or might not produce more or less color?
Hopefully at this point the separate blue species have species specific names, and because they are rare, worth more than regular jewels (whether your LFS knows it or not.
But with a hybrid they would not be a pure species, and would have to be sold as a hybrid to be truthful, and legitimate, which to me would make them worthless.
I wouldn’t want to produce a mutt I would just like to enjoy having a pair of jewel cichlids, I’m not here for the money and if anything I can easily use the babies as food, I wouldn’t go to the extent of attempting to sell offspring or anything like that especially if they aren’t pure. But I agree in terms of classification, hybrids that enter the hobby through improper breeding does complicate matters especially when hybrids begin to spread, I mean we’ve seen it happen with Midas and Red Devils, I mean most of those being sold are usually a mix of the two unless they verified wild caught or F1’s or F2.