umm, perhaps someone who knows could fill in the dots, but Glazier and Murdoch aren't exactly strangers, right? could there be some reason murdoch would sell to the irish duo instead of direct to Glazier, if in fact he is trying to obtain a controlling interest?
Could it be that Murdoch, Glazier and the Irish guys are future partners? They might be planning to use the investment partnership of the Irish guys as the takeover vehicle. In this case, Murdoch isn't actually selling a stake, but relocating his holdings from bSkyb to the takeover entity. Can a 10% stake really block a squeeze-out in the UK? In the US, 10% makes the process more difficult (e.g. requires a long form merger vs. a short form) but can't prevent it.
Personally I think Murdock sells his shares simply because Utd share price is so over valued. It is very inflated because of the takeover rumor. The Irish guys bought the shares because they are gamblers. They think they can make a fortune if the takeovers do happen.