Sorry for the double post, but the answer to my question can be found here: http://qt-project.org/forums/viewthread/43380

tl;dr The version of Qt Creator shipped with all Windows builds of Qt 5.3.0 is built with MSVC 2010, thus the inclusion of the 2010sp1 redist. This redist has nothing to do with the installed Qt libraries.

I'm replying here because I wasn't able to edit my OP. Could an admin please mark the thread as solved? Thanks.