Wdired doesn't support flush-matching-lines; gets "Text is read only"

[Klotz, Leigh]

In Emacs 22 I was able to use toggle-read-only followed by flush-matching-lines 
to filter viewed files.
In Emacs 23, ^X^Q is now bound to dired-toggle-read-only and when I use 
flush-matching-lines I get "Text is read only."
A view of the source shows a custom variable kill-read-only-ok but it appears 
to have no effect on flush-matching-lines.

Is there a way to be able to let flush-matching-lines work on dired buffers to 
hide the view of non-relevant files without deleting the actual files?

Alternatively, is there another way to satisfy my use case of using a regular 
expression and individual hides to filter files from dired view?

Thank you,
Leigh.