I think the tablets to which you refer are the laptops with tuckaway keyboards and stylus input. The tablets that Microsoft are talking about are more akin to the iPad - basically a mobile device with a bigger screen and a touch interface. Their equivalent of an iOS device.
As well as the usual performance and security issues with Flash, you have to be aware that a touch interface is a very different beast to a keyboard/mouse/stylus type interface. There will be gestures, taps (instead of clicks), for example. A touch interface has no “mouseover” or “hover” equivalent events, for example. While you may have been able to do this with a stylus (lightly touching the screen, in effect using the stylus as a mouse to move a pointer), such input is not possible in a touch interface. The OS itself will no doubt be built to handle these itself, but Flash will also need to conform to these. Now it may be possible for Flash to pass gestures form the OS input to the Flash animation running, but if that animation is not listening out for such gestures or input, then it won’t work or will work poorly. To cut a long story short, all Flash content on the web would have to be redone for touch interfaces. Can you see that happening? Neither do it.
Anyway, Microsoft hasn’t singled Flash out for special treatment. Just like Safari on the iSO devices, there are no plugins allowed. Flash is the high profile victim, but every single plugin you like in IE will not be installable on a Windows 8 mobile device,
