Test tube Burger?

Much excitement in the media about a £250,000 beef burger grown in a vat in the Netherlands from bovine stem cells (undifferentiated cells that can be persuaded to develop into any other cell type, including muscle). The cells had to be 'exercised' with electricity and the product, flavoured and dyed but the project was greeted with enthusiasm by some animal welfare groups who see it as a technique to reduce animal suffering by removing actual meat animals from the equation (http://www.theguardian.com/science/poll/2013/aug/05/stem-cells-meat-industry?INTCMP=SRCH).  There are some downsides to this (even if the process can be scaled up and made much cheaper) in that the eating activities of cattle are useful in modifying grasslands for biodiversity, there actually would be many fewer animals to see and farming could be largely changed to a wholly industrial process (to a much greater extent than factory farming). One point that hasn't been mentioned is that human stem cells would actually produce a protein closer to that containing our optimal balance of amino acids. So why not use these in the process? Or would this be cannibalism?