The way I read it, it means that investment market is so pitiful that MSFT looks "attractive" by offering a little bit of nothing for their bond sale.
I would say part of the explanation is that groupthink has induced investors to believe 0.9% on a MFST bond is better than what they can get investing in, say, blue-chip stocks.
“The efficient-market hypothesis may be the foremost piece of B.S. ever promulgated in any area of human knowledge!”