I'm finding it frustrating to explain to new incoming tenants why they have to pay a huge fee just to live in my condo.

This could probably be explained away with some good communication from your agent to the underwriter.  

Can you please explain further of what you mean by refinancing? 

How do I explain this to the seller’s agent in a non “logic bully” way?

The Doctor says, and this is the answer to your main question, "Don't raise your arm".I hate to be the one telling you this, but every paragraph you wrote above tells me you shouldn't go into REI.If you want details on why, let me know...I would be more than willing to explain.

Anyone care to explain on that topic?

Stay consistent as you may need to contact these owners 10-15 times before they agree to sell to you.Let me know if you have any other questions, and check out this article from Forbes explaining different types of motivated sellers. https://www.forbes.com/sites/f... 

The tenant also sent me a personal letter explaining her situation to me.

You could but when he explains the situation do you think you're walking away free?

The picture below explains the quote I opened with a bit more.