Someone at Apple is going "we have had iOS 6 in beta for months now; is this really the first time anyone noticed this issue?".
Additionally, the first iOS 6 betas had the browser in such a bad shape that it was obvious they were still working on it. I took one look at it and figured "i'll test it when they're done". They need to have some sort of clear indication of when it's actually ready for testing (and not just for testing of the native SDK's).
Maybe I am living in a bubble but every single web developer I have ever met used a Mac. Why ? Because it is the only platform that has Photoshop + a UNIX shell.
Also, cygwin.
And Cygwin is a joke. Dealing with the page separator differences alone would make it unbearable.
There's more Macs at the Edinburgh Ruby user group meeting than at the Mac user group meeting!
However, for your ability to test in the future: the only thing I believe the iOS beta requires related to owning a Mac is that the downloads from Apple's website for the IPSW files are stored inside of disk image files; you only need access to a Mac long enough to restore your device, but I am not certain why you would need a Mac to work with it later. (I would love to be told I was wrong there, however, so I could add that to the list of endemic issues leading to this.)