I haven't tested this particular scenario, but I would expect that TRIM does NOT wipe small file MFT content.
TRIM wipes a deallocated (deleted) file.
The MFT is a file. Removal of a small file entry from the MFT deallocates the MFT entry header, marking it as available. The MFT file is not deleted, so TRIM would not run against an entry in the MFT.