If abortion is a choice then why do pro-choicers hate when people choose life?

Pam Tebow and her son Tim Tebow (2007 Heisman Trophy winner) will be in a 30 second Super Bowl Commercial. The commercial is about how Pam was told by doctors to have an abortion but decided not to and went through her difficult pregnancy to give Tim a chance. Pro-Choice groups tried to get CBS to pull the ad but CBS is going to air it. Why are the pro-choicers in an uproar? Women need to know their really is a choice and in that choice they can choose life. Is it so wrong to tell that to people?