That's a part of the problem with colorizing. When shooting B/W you shoot differently than when shooting color. Maybe not on the snapshot level (like taking a picture with your phone!!) but when pros go out to choose a location and decide when to click the shutter, the type of film makes a difference. I have heard some pros have two cameras pointed at the same place, one b/w and the other color, so this isn't a hard and fast rule.
Another problem with colorizing is many b/w films were orthochromatic, they were not red sensitive, so reds come out darker in a print and blues/greens come out lighter. You can't fix this with colorizing. You may be able to fiddle with an image in Photoshop to get the 'look' in a b/w image though.
Still, I'd rather people concentrated on their own great photos of the current stuff than screwing with other's images.