Why do you think George Gey agreed to share the cells with any scientist who requested them? Do you think it was a good idea, based on what you know at this point in the story?
You didn't specify which part of the book you had read to, so when you ask, "at this point in the story," I can only assume you have read up to or around Ch. 13 where we know that Gey is sending out samples.
In Ch. 13, Skloot explains the distribution of the HeLa cells following Henrietta's death. At first Gey needed to see how hardy they were and what value they might have, and he did this by shipping them all over the country. He quickly found they were very hardy and even more susceptible to disease than normal cells, which was a good thing in scientific research.
It appears he began sharing cells with other scientists, truly, as a way of helping in scientific research and for the development of vaccines. For example, Skloot says in Ch. 13 that the National Foundation for Infantile Parlalysis contacted him for samples so they could work on a polio vaccine, which he was all too happy to get involved with. From Skloot's descriptions, it sounds as though earning money from the cells was not his initial intention. Had it been, he could have done things differently to take more credit for his work.
For example, she says:
"Many of Gey's colleagues pressured him to publish research papers so he could get credit for his work, but he always said he was too busy. He stayed up all night to work. He applied for extensions on grants, often took months to answer letters..." and so on" (Skloot).
He was too busy developing ways to prepare, ship, and utilize the cells. Later, as the cells began to be used by so many scientists across the world,
Gey was relieved that companies had taken over HeLa distribution so that he didn't have to do it himself, but he didn't like the fact that HeLa was now completely out of his control" (Skloot).
So, given what we know up to Ch. 13, it appears that George Gey shared the cells with other scientists in the interest of science and medicine.
Whether or not this was a good idea would be based on how you view his actions. He did send them out prior to doing much research on them and one of his chief complaints later was that people were using the cells in all sorts of ways and storing them in different mediums, so results might be unreliable. In other words, more uniformity in the processing of the cells was needed. He could have established those guidelines prior to sending out the cells, but that seemed to be an afterthought and long after the cells had been used for years by thousands of labs. So, you could argue it was not a good idea to send the cells out so early in his research process. You could also argue that it was a good idea because in doing so he was better able to determine their overall value, hardiness, and purposes.