I think you will be often but not always right about the motivations you are suggesting we read into the word "life." Many abortion critics do Directly Argue the Connotation that a fertilized egg is alive with a capital A L I V E, as part of a package of arguments of mixed quality. (If you wanted to emphasize that the total quality of these arguments is usually low, I wouldn't object). The connotation is not even always about human life: at one time there was a Salt Lake City based pro-life vegan punk rock community, whose package of views was unusually coherent for antisocial teenagers.