That the Twins are actively courting there own re-treads certainly tells you how little interest even run-of-the-mill non-Twins FA SPs have in even considering the Twins as a legit landing place.
I'm not sure it's true in this case, but I think it says more about how rumors are generated than anything else....
1) Ever notice that there are always more rumors about players that have been on a team than new players to a team? I think that's because the local media KNOWS these players. They can say "Hi" to them. And the easiest question to ask is "So, have you talked to the Twins?" We hera about Liriano and Pavano because a Twins beat writer is unlikely to stop and ask (random free agent starter) about the Twins, but he'll stop and talk to Frankie and Carl.
Anyway, I almost always take these rumors about returning players with a large grain of salt.
2) In this particular case, I'll speculate that Frankie's agent would be more than anxious to publicly hint at any kind of interest the Twins had with Frankie. He's trying to rebuild some value for a guy that has all kinds of questions about his stability. What better way to do that than to point out that the organization that knows him best is open to him returning?