It's based on this incident. [0]

Contrary to some aviation experts on YT, mast bumping and catastrophic mast separation in the 206 is possible with debris in the oil restrictor to the freewheeling unit.

0. https://www.tsb.gc.ca/eng/rapports-reports/aviation/2011/a11...

In relation to the https://asn.flightsafety.org/wikibase/268724

and

https://asn.flightsafety.org/wikibase/495847