Short answer: The bounty hunters catching renegade androids doesn't help the Rosen Co.'s public image at all, because the civilian populace doesn't know that there even are renegade androids to begin with. Instead, it just makes the Rosen Co. nervous because you have a bunch of cops going around testing to see if people are androids while the Rosen Co. has illegally created androids that they specifically want to stay on earth, such as Rachel and the fake police force.
Longer answer: Like any other evil mega-corporation, the Rosen Co. doesn't want the government breathing down its neck. Their ultimate goal is to create an android that is completely indistinguishable from an actual human, however as long as the government is obsessed over catching runaway androids and being able to "test" them to see the difference, it's likely that they'll serve as a stumbling block in the Rosen Co. accomplishing this goal. Also, as the existing tests for androids become outdated (its quite clear that the Rosen Co. believe they actually will) the government will pour in tons of money and resources to develop other tests. This means that 1) They will keep trying to impose restrictions on the company in order to make sure that there are measurable differences between humans and androids. 2) If the government would just quit with their tests already then Rosen Co. could just claim (to themselves and to their high-end clients who purchase androids for romantic use, etc.) that they've created an android that's indistinguishable and call it a day already.