Neat. I gave it a test.
The right edge now hovers the decoration button, and so does the corner and top edge. However, the top edge and corner still show the "resize" cursors even though you can't resize at that location anymore (it presses the button). Can you confirm that behaviour?
I first tested the master behaviour, then recompiled with the patch and tested the new behaviour.
Now that I think about it, this is fine as-is. You actually can resize a tiled window (unlike a maximized window), so the cursor is giving you accurate information. If you click, the window button will activate, as it visually suggests it will, but if you click and drag, it will resize the window.
In any case, this cannot be fixed in breeze, as far as I know.
The shape of the cursor is set either in kwin or kdecoration2, not in breeze.
Should file a bug against kwin, if this really is an issue.