Essentially what is happening is these are the roughly 30 or so Class IDs associated to various different installs of MS 2010 products such as Office Standard, Office Pro Plus, Office Home and Student, Office Pro, Project Pro, Project Std, Visio Pro, and individual app installs such as Word, Excel, Outlook, PowerPoint, and Access.
Very basically, if what is installed natively doesn't match with what is packaged with ThinApp, then there are license activation issues.
Since ThinApp runtime loads the reg hives from top to bottom, deleting everything up front (at the top of the Local Machine registry hive) allows for the ThinApp package to only see just what it needs and none of the native settings which may interfere (as there are invariably going to be a couple of these further on down in the Local Machine hive for your ThinApp package of whatever MS 2010 product you are packaging - meaning ThinApp will load these as needed).
In short, by adding these values to the HKEY_LOCAL_MACHINE.TXT registry hive file, you are helping ThinApp properly isolate the MS 2010 app in question from whatever native settings in order for the ThinApp package to load and work correctly.
Hope this helps explain what is going on here. :-)