They certainly can go after HIM, and they will. He was obligated as the executor to pay those things before distributing any money. He can go after the other beneficiaries to try to recover some of the money distributed.
You don't have to accept.
The executor is personally responsible to the IRS to the extent of the improper distributions that were made, and the IRS may also go after the beneficiaries to the extent of the distributions they received.
The problem is, he didn't decline to act, he was just incompetent.
I had a client who was the executor of an estate. The deceased had a large amount of cash that she was leaving to multiple relatives and she left her house to him. He made the mistake of not doing her final, personal tax return until after he had made the distributions. She ended up owing a very large amount of tax. The IRS went after the executor and the executor had to go after the other heirs.
Exactly why the executor should be getting competent legal and tax advice for the estate. I advise my executor clients not to ensure that the estate retains sufficient assets to pay all the debts, including any tax liabilities that may arise from returns yet to be filed or from audits by tax agencies. For the IRS I will generally seek a closing letter for the estate before giving the ok for distributions. Executors that are overly eager to get the estate distributed fast sometimes shoot themselves in the foot in the process when they discover debts that had yet to be paid later on with no estate assets left to pay them.
Did an heir named or by law have to receive something from the estate in order to be liable for repayment? How was/should the recovery been apportioned - equally or propotionally to the value received?
What do you do when the executor refuses to seek legal counsel or file for a small estate? The value of the probate estate is in personal property which the executor either is claiming and would refuse to sell or has already given to charity.
How the executor goes after the beneficiaries depends on the applicable state law, and states have varying rules for this.
If the executor refuses to consult lawyers and tax professionals then the executor put himself/herself at risk for being liable to the creditors. Beneficiaries can try to hold the executor accountable to pay bills, but in the end they have to realize that if creditors of the estate come after them for payment they may have to cough up some or all of what they received from the estate. Thus, beneficiaries should not be quick to spend what they get.