That type of situation could make anyone uneasy and make trusting Ash or other people a lot more difficult.
If it were during such a critical time when anything could go wrong as a result of Cerberus acting on what had been given to them, then it would not be so easy to put complete trust in Ash to the point of letting her escape their grasp and vanish.
It was especially the case if something else was going on that Ross had not yet been able to figure out.
Letting her leave like that was far too risky, so Ross started to reconsider his decision once more.
It could be just as easy for her to seek out other ways to make money if she were not fully loyal to Cerberus, especially since she still had things of value that others would want to get their hands on.
If Cerberus was unwilling to handle those things, then there were always others who would.
It was Ross's job to consider the big picture and to make decisions for the best of Cerberus.
