At the very least, offering a reward buys a missing person's family a bit of media exposure (before even a cent of it needs to be paid out, too). It can mean an opportunity to get Bob's story out again, to update the details on any posters, etc., they might want circulated. It can mean re-awakening public and LE interest in a case. If not with the trust money, could they not have put together some reward on their own? (Also, I've seen news releases for when rewards are increased, so starting with a lower sum is not even the worst thing; the public may want to make donations to it.) And if it was a matter of Bob's family not having any money on their own, how about fundraisers? These can help with money and exposure.
Why were none of these steps taken, even though offering a reward had been part of the alleged reason for the immediate attempts to control the trust? Did Bob's daughters completely fail to read anything on how families of missing people can try to help? Did not one daughter also work for a police department? I would have thought she, at least, would have some idea.
It makes me think that Bob's daughters are the last people who should be making 'blood money' accusations against him.