If RedHat internally keep patches separate and build from stock + patches then that's their preferred source. If the source they distribute has the patches applied in part to frustrate cloners, and if there is sufficient value in having the broken out patches that customer demand still forces them to make these available to customers, then that would clearly seem to make that form of redistribution be of source in a 'less preferred' form. Contrary to the GPL.
Think very carefully about defending RedHat here. While RedHat generally get Free Software and are reasonably trust-worthy, and we might feel like cutting them slack, there are plenty of other Linux distributors who don't. Particularly in the embedded world, if you can even get (all) the source, it's usually a giant tarball. To the extent such distributors keep patches separated out internally, users who buy such devices *should* be able to get at those patches. It's not a massive issue yet, because usually the changes they make are small enough that diffing is still tractable - but that need not always remain the case.
1. Even if they've apparently acquired some amount of middle-management that doesn't and may not be, according to daniel (which, if correct, makes for a long-term worry the community should have for RedHat: some of those middle-managers may progress to top-level management one day).