It's kind of a crude fix (because I don't understand how the script works well enough to do something more sophisticated), but you can edit the adminimize.php to restore your media buttons.
Open adminimize.php and go to around line 179 and find this:
if ( recursive_in_array('media_buttons', $disabled_metaboxes_post_all) )
and simply comment it out so:
// REMOVED TO RESTORE MEDIA BUTTONS
//if ( recursive_in_array('media_buttons', $disabled_metaboxes_post_all) )
I have a feeling, though, this will restore media buttons for ALL users who have access to the post/page editing page.
And also, of course, it is a hack, so if the author doesn't fix this in the next version and you upgrade, you'll have to hack the new plugin as well...