Block the plugin from just one page????

Hello Dan,
There are several plugins that allow to show widgets based on specific conditions. These plugins work for every type of widget, not just the TinyMCE ones:

Display Widgets: Clean and simple interface
Widget Context: It has a few more options than the previous one
Dynamic Widgets: This is the most rich of features
Widget Logic: This is aimed to programmers as you need to write the condition in PHP code. I.e. is_page(‘about’)

An alternative solution is given by the following plugin, which allows you to define a custom set of widgets on a per-page basis, directly from the edit page screen:

WP Page Widget