iOS 6 and Passcode Timer

You mean the "Require Password" section doesn't have 1 hour and 4 hours in it?
I just checked, and it's there for me.

Shorter times are more secure anyway..

 

Are you using an Exchange account for e-mail/calendar/contacts?

I believe Exchange has options to limit these options - may be worth checking out.

For the record, mine also only has up to 15 minutes. (I use two exchange accounts, Work, and Google.)

 

You may need to check what your organisation's settings are, my employer has the ability to wipe my phone remotely, prevent me browsing the web, restrict use of the camera etc if I set up my work exchange email. Needless to say I don't have work email on my phone anymore!