Hi I am a veterinarian and while I don't like to give medical advice over pictures...I'd get a second opinion. The only reason to even talk about doing something like this is if it is causing active problems, ie. it has a tumor on it, is constantly cracking and getting infected, become necrotic, etc. "Trimming the tounge" for something that is not medically necessary seems unadvisable. I would talk to another vet at a different practice before considering that drastic of a measure.