Ah, so did the polling method here just consist of blatantly making up numbers? Reminds me of Strategic Vision.
It's not entirely unlikely if you just assume all the undecideds break for Thompson. The district is probably the most raciall polarized in teh country, with the Republican getting more than 80% of the White vote and the Democrat getting more than 90% of the Black vote. The problem is that the district itself is actually 63.5% Black, which kind of destroys the Republican's chances.
Every undecided breaking for an incumbent? Yeah, that happens.