New tainting problem in 2.1 PTR

[Vangual]

While I was testing my addons on 2.1 I've hit some major tainting issues.

I've written a somewhat minimal test-case addon that essentially doesn't do anything other than create a few frames and secure buttons, and sets them some attributes to hide/show and react on mouseover using SecureAnchorEnter.

However simply loading this testcase addon will already taint most Action Buttons of other addons already and yield the following error:

[2007/04/28 22:03:42-749-x1]: <event>ADDON_ACTION_BLOCKED:AddOn 'TGBugTestCase' tried to call the protected function 'UNKNOWN'.
<in C code>: ?
<in C code>: ?
<in C code>: in function `UseAction'
Interface\FrameXML\SecureTemplates.lua:218: in function `SecureActionButton_OnClick':
<string>:"*:OnClick":1: in function <[string "*:OnClick"]:1>
(tail call): ?:
<in C code>: in function `securecall'
Interface\FrameXML\SecureStateHeader.lua:998: in function <Interface\FrameXML\SecureStateHeader.lua:979>:

You can download the standalone testcase addon here:
http://xplo.org/wow/addons/tg/TGBugTestCase.zip
Or for viewing convenience:
http://wowi.pastey.net/18679

Please note that I'm not very good with the secure state system yet, I've learned and gathered together my knowledge mostly by looking at existing Addons. As such you'll likely find something I'm doing wrong or unnecessary code, PLEASE point those stupidities out to me.

Did I hit a bug on 2.1 here or am I just doing something terribely wrong that was forbidden recently?

Edit1: This error is existing in build 0.1.0 6607