Interfering with telomere activity is a critical step for cancer progression (see the halmarks of cancer, limitless reproductive potential), so this procedure essentially makes every cell in your body pre-cancerous.
In my opinion, the most amazing part about this is that the way in which telomerase is delivered is via a retrovirus, typically a relative of HIV.
Since telomerase is not really an oncogene, I'm not sure that the notion of "pre-cancerous" that you're advocating has any meaning. By that token, nearly every cell is pre-cancerous, and in a fetus even more so.
In my opinion, the most amazing part about this is that the way in which telomerase is delivered is via a retrovirus, typically a relative of HIV.