I'd think that red tiger Oscars are labelled like that simply because they have even more red on them as the "normal" tiger Oscars. They're all the same species after all, so in the end what they are labelled is defined by their looks.
Can't see anything wrong really at wanting more money for the ones with more red, even though it's certainly for the profit. That is, as long as the ones labelled "red tiger Oscars" really have more red on them than the others, else it would be fooling the customers of course.