This is nonsense.
I'm pretty sure the London organization was vocal about the fact that they were never approached by the Las Vegas ownership group it at all and the notion they had any legal ability to block it is fuzzy at best. There is no realistic expectation that one would infringe on the other and there is already precedent for an OHL team to have the same name as an NHL team with Kitchener and New York. Somehow the public wasn't woefully confused by this situation.
Winnipeg re-acquired an NHL team and named it the Jets. Certainly you would think the NFL's New York Jets would be more powerful than the London Knights? They had no issue with Winnipeg having that franchise operating in several US markets. The New York Rangers and Texas Rangers share the same name. The Florida Panthers and Carolina Panthers co-exist. We have the Sacramento Kings and the Los Angeles Kings. There's the Carolina Hurricanes and the Miami Hurricanes (and the Lethbridge Hurricanes too.) The Houston Oilers and Edmonton Oilers were operating at the same time.
But somehow those multi-million dollar organizations had no power to stop a team in a different league from using the name but the London Knights were gonna pump the brakes on a half-a-billion operation that existed in another country hundreds of miles away?
Nope.
Most of your examples are between different sports so no confusion.
Kitchener and New York have a historical link, hence the shared name.
However, the statement "tonight's hockey game : Rangers vs Knights... See it live at 7pm" would definitely cause trademark confusion in southwest Ontario had Vegas not applied an adjective.
Really, Foley should have gotten over his ego and used a name that actually represented the area and totally move away from anything Knights related. Though, Las Vegas Desert Knights or even Las Vegas Silver Knights would have rolled off the tongue better.