Yes, if there was an economic advantage for them to do so. The question isn't "Is Redhat doing this now", the situation is "They can do this if they want, it's a free (market|country|source)". There's nothing stopping Redhat (or anyone else) selling support for Debian installs, and that's an advantage of open source.
Try selling support (including fixing underlying source code bugs) for a closed product. Only the company or affiliated vendors can do that, and poorly at that (usually). Less choice == !good