Why does deferred rendering flip the view and change the viewToWorldMatrix?

I'm issuing GL.IssuePluginEvent in a camera script's OnPostRender.

In forward, we get the following camera.worldToCameraMatrix:

 0.153904811        0.237111583        0.959214032        0.000000000
 
 0.988085806        -0.0369326770    -0.149407730    0.000000000
 
 0.000000000        0.970780134        -0.239970684    0.000000000    
 
 12.0400715        -164.576477        -133.301300        1.00000000
 

and when I draw text to screen:

But switch the same camera to Deferred rendering, and camera.worldToCameraMatrix is:

 -0.988085806    -0.0369326659    0.149407685        0.000000000
     
 -0.153904766    0.237111494        -0.959214032    0.000000000
     
 1.34547822e-008    -0.970780134    -0.239970595    -0.000000000
 
 12.0400715        164.576477        -133.301300        1.00000000

And onscreen text becomes:

Why? And how can I get my plugin code to reverse whatever has been done to the view in deferred mode?