Personally I'd walk away, life is too short to care about why a twitter user blocked you.
But seeing as this is in the EU, the author could use the GDPR to find out why he was banned.
But seeing as this is in the EU, the author could use the GDPR to find out why he was banned.
Of course if they just spontaneously clicked 'block user' whilst browsing twitter because they just didn't like something he wrote then the above would be moot.
And you would be surprised to know how frequent those are (not necessarily about Twitter but in general about customers/employees/visitors in shops etc.)
The above happened under the 1995 DPD regime, the GDPR would probably be even more useful.