There is no need to worry about the 'tongue' when lip locking a bass.
I am sorry you had a bad experience, but I'm a bit surprised about a reference to a 'bite' from a bass. Largemouth and smallmouth bass have sandpaper-like teeth, for the most part. I have heard that spotted bass, which is sort of sub-species of largemouth and don't grow as large, have more toothy teeth than Florida strain largemouth, and I have heard that ones that are primarily shad-feeders have sharper teeth than the ones with more worn teeth from feeding on crawfish, but I don't have any confirmation of that.
I can't say I have ever felt any trepidation over handling largemouth here in central NC, and I have liplocked a lot of 6 to 9 pound class fish... I actually consider it a little pride-booster when I come home with my 'bass fishing thumb' where my thumb is a bit scraped up and rough, but that's because it takes 15 to 20 bass in a day to get it that way. If you arch your thumb at nearly 90 degrees and grip hard when lip-locking a bass, I would think you should be able to avoid scrapes.
I would suggest that if you are feeling anxious, start carrying a pair of fish-grips with which to grab them, or slide a finger up under the uppermost gill plate to hold them... I don't like to damage their gills, so I would opt for a pair of needle-nose or grips on their jaw, personally.
Lastly, you're sure this was a largemouth bass you were holding? Where were you fishing, region-wise? Just curious.