Safety of Sous-Vide for long cooking times

The searing applied after sous-viding should not be enough to alter the temperature of the meat notably. All you're trying to do with the sear is create the flavorful crust on the outside of a piece of meat via the Maillard reaction, not accomplish any cooking of the interior of the meat itself. This is best done by applying very high heat for a very short amount time, usually just a few seconds. Some like doing this via pan-searing or on a very hot grill, but I usually use a high-powered blowtorch. The important thing is that you not sear for so long that interior of the meat has a chance to notice. A perfectly sous-vided piece of meat should be a uniform color throughout, except for a heavily seared crust. There shouldn't be any gray band of over-cooked meat under the crust. Avoiding that is why you're sous-viding in the first place.

Also, I find 125-130°F to be a touch on the rare side. For a good medium rare, 133-135°F gives me better results.

Sirloin steak doesn't have a huge amount of collegen, which is why it's traditionally cooked over high heat for as short a period of time as possible. If I were you I'd be more worried about the meat become unpleasantly mushy if left in the bath for too long. I would just use the Douglas Baldwin tables for bringing the meat up to the required temperature:

Heating Time from 41°F (5°C) to 1°F (0.5°C) Less Than the Water Bath’s Temperature

Thickness   Slab-like   Cylinder-like   Sphere-like
  15 mm       35 min       18 min          13 min
  20 mm       50 min       30 min          20 min
  25 mm       1¼ hr        40 min          25 min