Toddler + Cats = Problems

I have two old lady cats who are mother and daughter. Their names are Evette (mother) and Goose (daughter). Evette is crotchety and fluffy and loves affection and your lap. Goose is white and squishy and bizarrely scared of almost anyone who is not Jeremy or I. She used to play fetch when she was a kitten, and sit out on the stoop with me impressing all my neighbors, and dogs of my neighbors even more. I've had them both for about 10 years, so this is not a new relationship. We go way back.

One year ago we added Isaac to our mix. It was very easy at first. The cats stayed away from him and he didn't notice them.  Then he did notice but couldn't give chase.  Now it's totally different. He wants them bad. He wants to squeeze and shake them like big furry maracas, and they are having none of that. Goose runs away really low to the ground, or moans and hisses at him. She's even scratched him once. I tell him over and over, "Don't mess with the Goose!", but he doesn't listen.

Before the danger set in.

 Evette thinks if she holds really still and just twitches her tail a little bit he won't see her, but of course that doesn't work at all. He grabs her and squeals, or plays a maniacal game of patty cake, and then grabs. "No Isaac!, Gentle!", I say. Then I pet him like I want him to pet Evette, "Gennnntle."

The only thing that works is to sequester them in our room. It's a bummer, but I don't know what else to do. Any suggestions?

Back in May, when we didn't grab and were a happy kitty-baby family

Happier kitty note: I just found a Australian kitty website called Flippy's Cat Page. The lady who runs it obviously loves cats like crazy. One of the pages on it has a super long list of kitty names (6,300). Some of them really make me laugh.
A few highlights: Lord Chrysanthemum, Mervette, Sheepish Lion Lampert, and Baby Bookins.  Funny, there was no Goose or Evette!