In my humble opinion, Sony Corp. have been over confident in making the said demand, because protection given by trademark registration is limited to certain types/kinds of products covered by said trademark. 
Kwa maoni yangu binafsi, Shirika la Sony lilitoa madai hayo kwa kujiamini mno, kwa sababu kinga inayotolewa wakati wa usajili wa nembo huwa inahusu aina fulani tu ya bidhaa iliyo chini ya nembo husika.