People had to get a certain number of flying hours to get flight pay but that had nothing to do with the last month of the fiscal year. 3400 funds, those are Operation and Maintenance funds, not military pay funds, expire at the end of the fiscal year, and any that expire will serve as basis to cut the budget for the following years. So there is always a mad scramble to spend the money before it expires. This reaches a high degree of absurdity. I recall once when our boss was called in to explain why we had spent 50% of our travel budget for the year and his response was that the year was 50% complete! The norm is to save up your travel money in case you need it and then invent reasons to spend it before it expires. Our branch never did that, instead sending our engineers out to respond to problems as required; the fact that our boss had to explain that we were on track on spending our travel money shows how absurd things could get.
Now, the other thing that expires at the end of the FY is leave days You can only carry so many over to the next FY and any over that amount expires. So there is scramble to use up leave before the end of the FY as well. I'd guess the 27 people who were on that RB-36 either were on travel to use up those funds on a useless trip to some place they wanted to go or had hopped a ride so they could use up leave at a place where they wanted to go, where the B-36 was originally scheduled to land. One favorite target for B-36 missions was Puerto Rico, so maybe they planned to land at Eglin or somewhere on the way back.