There's a chance it's fake, potentially from someone seeking to get attention, or from someone trying to scare KF users from returning to the site. There's also a chance it's just the authorities requesting a statement but the person isn't in any real legal trouble.
One thing to keep in mind, the UK and a lot of Europe are unique in how shit they are with free speech. You can actually find cases in the UK specifically where teenagers have been prosecuted for posting rap lyrics that contained the word "Yamanba" on social media. Count Dankula was not some exceedingly unique case over there, outside of the fact that he fought it so heavily as most just cave in, make an apology and get probation.
This is something people don't really get, the idea of freedom of speech does not exist in the EU, and it's not like it exists in spirit despite not existing in name. People get fucked over constantly for making retarded social media posts or doing dumb shit that in the USA wouldn't even get a second look.
Edit: For reference from the BBC:
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Chelsea Russell said she used the Snap Dogg lyric as a tribute to a boy who died in a crash.
www.bbc.com