Apple publishes that IP range (CIDR address block) in several KB articles on its own website for system administrators to configure firewalls/web filters.
It's been done before, (e.g Intel has been called out for consuming kernel.org bandwidth and git CPU power) and is the simplest way to have people from inside BigCorp get a message.
But reviewing the thread I see you your question was in response to someone calling them "service providers" to Apple. So your question was entirely justified and it was me who'd lost context.
I want to add an answer that to those saying that gives information about Apple: it only says that somehow, one team inside Apple has setup a CI (badly written script) with maybe 5k tests (from a standard set for instance) and has 9 commits per day. Or maybe they have more commits, and less tests ? Or maybe, it's a matrix of 70x70 tests. Or maybe… well, all it says is that someone is experimenting with this.
Someone you get freebies from isn't a "service provider".