If the question is whether customers will "accept" the miles, the answer is yes. Or they won't get anything. That is because what is being described is not some form of mandatory compensation, but rather a customer service gesture in UA's discretion.
The vast majority of customers don't and won't overthink this. They will see 5,000 as a lot of miles and be done with it.
Those who are required to use vouchers received while on third-party, e.g. employer-paid travel, for that type of travel will be quite happy because it is close to impossible for employers to track miles.