If you could pile all HeLa cells ever grown onto a scale, they’d weigh more than 50 million metric tons — more than 100 Empire State Buildings. If a culture flask could generate 100g of cells (which I think is high; I seem to recall getting on the order of 20ml of spun cells from a 1L flask), that would correspond to 500 billion culture flasks. At $5 per flask that's $2.5 trillion just for the flasks (ignoring costs for other disposables, media (expensive!), BL2 facilities, etc). If you start from 10 grams it's only 42 doublings (with no consumption of results) to get to 5.0E13 grams. HeLa doubles in a day, so if you could have that population in a huge, sterile swimming pool filled with replenished media and enough space (suspension or surface, not sure what's needed) you could get your 100 Empire State buildings in a month and a half. I think it's possible the author was told that the HeLa line had gone through 42 (or some such) passages, and simply did 2^N to arrive at their number.

There is a huge difference between experimenting on a person without their consent and using cells harvested from their body without it. There is no significant consciousness associated with a culture dish of cells. The idea of personal ownership of one's cells apart from our bodies is, I think, simply silly.