Sure he's arrogant but I wouldn't rank his accomplishments and person hood by tweets. He has an incredible record as an engineering manager and investor and to brush that off is just silly.
I will brush that off, because the character of our leadership matters. It would be a regrettable outcome if our next generation of leaders acts as boorishly as Elon Musk does. We want leaders who inspire others to be the best version of themselves, and that includes treating others with respect and care.
I read this as a polite way of saying he's up his own arse, which seems accurate.