As far as Khabib goes, I believe the adage is:
"don't start nothin', won't be nothin'" - Mahatma Gandhi
And Khabib isn't even what made that situation ugly. It was a bunch of totally unrelated people getting showered with broken glass and missing fights.
Really Conor's bus incident probably doesn't crack the top 20 as far as lowest acts in MMA history IMO. I'd consider it worse to attack someone who's not a fighter. Just thinking of guys who did time or where the courts got involved, there's a lot of ugly histories in MMA
The Contenders (mostly top of my head had to google some names):
- Joe Son commiting rape, murder, and sexually assaulting Keith Hackney's fist
- Ali's whole terrorist/FBI informant thing.
- War Machine,
- Charles Bennet,
- Thiago Silva's armed standoff with the swat team (i believe related charges were dropped, but the standoff 100% happened and was not a great look),
- Rampage's rampage,
- Hermes Franka was arrested for raping kids,
- Mayhem's whole life,
- Alexander Emelianenko did time for sexual assault,
- I think Bowles was cooking meth or something
- Chael commiting fraud wasn't great
- Penn hit a cop once
- Dmitry Sosnovskiy kidnapped someone
- Jones whole life
- Rumble's domestic violence
- Lee Murray's heist
- Josh Grispi's domestic violence
- One of the sweedish guys had a burglary rap
- Irwin Rivera's attempted murder rap
- One of the AMA guys got arrested for assaulting a cop on Jan 6th
- Travis Fulton was arrested for child porn
- Tony Ferguson's domestic violence
- Matt Hughes domestic violence
- Melvin Guillard's bar fights
- Mike Perry's bar fights
- Abel Trujillo was sending dick pics to kids or something
- Jarrod Wyatt cut his buddy's heart out