First of all, I want to thank you all for your input. Your opinions and discussions have helped me through this stressful incident. Great discussions and insight.
To clarify, the old scoutmaster is working with the new scoutmaster and the chair. They were the ones advising me to write the check without receipts to defer costs involved with attaining eagle. The money is not the issue because we have a pretty strong fundraiser. I know some of you asked for more details, I am leaving some things vague intentionally, because I do not want to publicly shame anyone involved.
In the end I said "No receipt, no check. If you don't like it, 'fire' me." This after explaining the tax implications, the bad precedent it would set, the accounting problems, etc.
It made a few people angry (and I think some still think I am being unreasonable) but in the end they agreed to submit receipts. And we are doing the right thing!
Thanks so much for your time! I was really starting to doubt myself until reading your input.