From the unified rules and other important regulations:
"17. Types of Contest Results
- Submission by:
- Physical Tap Out
- Verbal Tap Out
- Knockout by:
- when Referee stops the contest (TKO)
- when an injury as a result of a legal maneuver is sever enough to terminate a bout (TKO)
- when contestant being rendered unconscious due strikes or kicks (KO)
- Decision via the scorecards, including:
- Unanimous Decision - When all three judges score the contest for the same contestant
- Split Decision - When two judges score the contest for one contestant and one judge scores for the opponent
- Majority Decision - When two judges score the contest for the same contestant and one judge scores a draw
- Draws, including:
- Unanimous Draw - When all three judges score the contest a draw
- Majority Draw - When two judges score the contest a draw
- Split Draw - When all three judges score differently
- Disqulification
- Forfeit
- Technical Draw
- Technical Decision
- No Decision "
I don't see the option for the referee to stop the submision without a tap out. I guess kevin lee won by tko via rear naked choke.