Alix was already on record as nearly causing a diplomatic incident by refusing to greet his grandfather on an informal occasion before she backed down and did it.
Her vitriolic loathing of Prussia and Germany by extension had quite far-reaching consequences, such as refusing to allow any of her children to marry a German even had they not absorbed her views about them.
Also, I suspect GraceOMalleysGhost was joking. I had much the same reaction minus the physical injury in Alexandra's thread. Alix described the occasion with 'The Great William' rather acidly.
Willy, of course, would not think it at all strange to buy Sisi's old house in Corfu and hang around in Greece despite once banning his sister from Germany with hellfire and damnation for converting to Greek Orthodoxy...