presumably because Intel does not have access to the necessary hardware configurations to test the fixes on?

I couldn't accept this as an excuse when you have possibly the worst CPU bug in x86 history, or perhaps all CPU history, with ample of man power and resources, along with 6 months time frame.

Rush isn't a word I would use.

I highly doubt this, given how much hardware they appear have lying around to throw at the Linux 0day Test Bot (which does full kernel compiles, boots, and integration tests for dozens of hardware configurations for every patch sent to most LKML lists).

No, because they don't have access to all the software in the world.