Dealing with irrational requests

My uncle has an aide that comes over M -Th 11-3. She mentioned once that she’s allergic to bees, he is now convinced that she is highly allergic and needs an EpiPen in the event that she is stung and goes into shock. She has said that she’s not that allergic and she’ll be fine but he is fixated on this being dangerous.

He has asked her to get an EpiPen and when she didn’t he was very upset, saying that this isn’t safe. He’s also worried that if she is stung that something will happen and I will be sued since I’m his POA and that it could be unsafe for everyone.

I can’t reason with him, obviously, and he won’t listen to me saying that this is her choice and not his. If I don’t “do something” about this he will use it as evidence that I’m incapable of helping him. I listened to his concerns and said I’d think about it.

A few weeks ago he was upset that his aide has a slippery floor in her car (on the passenger’s side, he was convinced he would slip while getting in the car). He was very angry and our neighbors helped soothe him and gave him a carpet to put in her car, but he threatened to charge the aide and I with elder abuse since we didn’t do anything about it. He changed his mind but this is the territory we’re entering and I’m not sure what to do.

Any ideas?