Can someone else try this and see if you get the same results? I am wondering if rootless needs to be turned back off, in order to turn off TRIM in the app.
What Trim Enabler basically does is "patch" the corresponding Apple kernel extension by basically disabling the check whether the given SSD is on the "Apple white list".
Tampering ("writing") with kernel extensions is now forbidden, when the new feature "rootless" is enabled: even as "root" you cannot overwrite those system kernel extensions.
I haven't tried it myself, but since "turning off" Trim Enabler implies "patching" the Apple kernel extension again by restoring it to its original state, means: "write it again", I would very much expect that you have to disable "rootless" again in order to do so.
(Once Trim Enabler has messed around with that kernel extension, you can obviously enable "rootless" again - but what comes a bit of a surprise to me that it is then obviously not necessary to still disable "kernel extension signature check", once you have enabled TRIM. Also see my previous post).
Sounds logical, no?