RE:silence is concerning You're not telling the whole story here. It was a partial sell and it is part of his investment framework (known before the initial buy recommendation). His sell condition isn't even met, so if his readers sold, they are poor readers. He remained very confident & bullish on the long term of the company.
Big swings in this type of stocks is perfectly normal to me. But i do agree that some more news on progress would be more then welcome.