As an American citizen, the primary risk in using an AML/KYC exchange with identity requirements would be the exchange reporting financial transactions to the IRS. This would be done to identify potential money laundering and/or unreported capital gains. However, in the case of buybacks, the Nu blockchain can verify that all shares purchased have been destroyed. This means that you would not realize any capital gains/losses, and instead would be acting as a contracted agent for the network. This might actually be an argument for forgoing payment, so that an executor could state that they were voluntarily destroying shares for the network, if they were questioned.
The other risk in using an AML/KYC exchange is if you are seen to be issuing new securities in violation of existing regulations. It’s debatable whether NuShares even qualify as a security (most of us view them as equity in a company that allows all shareholders to act as managers, through blockchain-based decision making like custodial grants and parking rates), but luckily with buybacks there is no new issuance of NSR.
Are there any specific concerns you have that shareholders could help research? With Level 3 and your established community trust, I would be willing to vote for you.