If Jim is being threatened with lawsuits then you must comply with Jim's request to provide written permission from the artist.
Basically what you are doing in posting all the cartoons in one place, is robbing those other sites of the internet traffic the cartoons generate.
That affects what those sites charge to advertise.
Jim is not being mean and hard on you, it's the nature of internet business.
Funny thing is: Pookie has actually turned me, and probably a lot of people, on to toon's we would have never seen otherwise. I go visit a few sites that either carry, an artist toon's, or the artist's site itself because of her.
Of course I understand Jim's position, but he ought to tell them it is, or can be, a form of free advertising for them.
Of course; Not that those lame brains in the MSM would listen or understand.
It gives more exposure to the cartoonist and may draw people to their sites. This stance by them to protect their proprietary info will only ensure that this reader ignores them in the future.