Well, I suppose the best thing to do for now, if for some reason your proposed use of FlashTwitter is not covered by the GNU General Public License is to get in touch.
Click the "contact" link in the footer of this page to email Steve Jones at G-RAFF.
FlashTwitter by Steve Jones @ G-RAFF is licensed under a GNU General Public License.
Permissions beyond the scope of this license may be available here