so that they can avoid gcc 4.3+, when it went GPLv3. It was hard enough for them before: gcc was the one place they have been unable to redact and hoard their ARM contributions, but with GPLv3 the situation becomes untenable for them.
How come GPLv3 (as opposed to GPLv2) is not in Apple's liking?
I actually am not certain, but if you'd like to hear it from the horse's mouth you can read this post to the gcc mailing list from an Apple employee, and follow the remainder of the thread:
For more details from other people who were discussing this issue, you can read a later thread that attempted to go into further detail, although I will not claim it will be elucidating:
How come GPLv3 (as opposed to GPLv2) is not in Apple's liking?