I just went through all of this today with a clean, 2008 R2 AD, Win 7 Pro x86, View 5.2.0 and still cannot adjust the font size. I followed your suggestion, and what is interesting about it is that the User Configuration/Policies/Administrative Templates/Control Panel/Personalization/Prohibit selection of visual font size setting only applies to "Windows Server 2003, Windows XP, and Windows 2000 operating systems only" according to the Group Policy Editor in Windows Server 2008 R2. I confirmed this when I modeled the effect of the policy setting against a Windows 7 target computer, because it will not apply it.
Therefore, there must be something else you did, or some "other" policy settings that makes this work.