IRA RMD included in rollover to 403(b) - Distribute as excess?

A participant did not remove his 2019 IRA RMD prior to the rollover to his 403(b) earlier this year. Approximately $4000 was not eligible for rollover. I understand the 2019 IRA RMD cannot be satisfied by simply cashing it out of the 403(b), but can the IRA RMD amount be treated as an excess in the 403(b) and pushed to the participant that way? That is how the sending firm wants it to be treated. Would treating it as an excess also satisfy the IRA RMD?  I am not familiar with treating RMD amounts as excess and could use some guidance. TIA

The best way would be to return the RMD plus earnings to the participant's IRA and have them take the RMD from the IRA where the funds are deposited. It doesn't necessarily have to be the same IRA that sent the funds for rollover.

I'm assuming the participant doesn't have a separate IRA they could take the RMD from but it wouldn't hurt to ask.

They do not have another IRA. Also, the IRA firm will not provide a Letter of Acceptance (LOA) to the 403(b) firm. Can the 403(b) push it back without a LOA?

I am also curious, if the 403(b) pushed the $4000 IRA RMD out to the participant, is coding it as an excess contribution even correct?