The listing states "One Kommando may be upgraded to Nob +10 points".
So that would cap the unit at a max of 15 as you upgrade one of the 5-15 kommandos.
For Snikrot the exact wording in the list is:
"Instead of a Nob, one mob may be led by: - Boss Snikrot (see page 62).... 85 points"
So instead of upgrading a kommando to a Nob, you but Snikrot (there is no + in front of his points cost, so it is 85 not 85+10).
I would say you still cap of at 15 as you are still replacing the option of a regular commando with Snikrot (just as you do when you take a nob).
For people reading along page 99 of the latest Ork Codex.