"By whom would it have been presumed? [to be racist]"
By Baz, or you or me or just about anybody else, Andy:
Recommendations 12, 13 and 14 (of 70) of the MacPherson report into the Met’s handling of the death of Stephen Lawrence:
DEFINITION OF RACIST INCIDENT
12. That the definition should be: "A racist incident is any incident which is perceived to be racist by the victim or any other person".
13. That the term "racist incident" must be understood to include crimes and non-crimes in policing terms. Both must be reported, recorded and investigated with equal commitment.
14. That this definition should be universally adopted by the Police, local
Government and other relevant agencies.
"so every time a white man lashes out at a black man it'll be considered racist?"
So long as the victim, you or me or anybody else considers it so then, yes. (See above). I hope you'll find that ridiculous because I always have, ever since the report was published.