Does IS help with slow moving subjects?

Really? Let's look at EXACT quotes from the OP.

Msg title: Does IS help with slow moving subjects?

He didn't ask if IS "stilled the movement" he asked if it helps.

And the answer to that question is: YES, it will help - if the shutter speed of the camera is fast enough to stop the motion but still to slow to prevent camera shake.

Let's look inside the post at the 2 questions (identified by the "?" at the end):

"But what about slow moving subjects in low light, for example school plays, people at a dinner party, award ceremonies?

Would there be a benefit from using a estabilized lens vs non IS?:"

The answer is the same.

At no point did he ask the specific question you are so adamant he asked "does af/is assist in stilling the movement of subjects". I'm not sure where you saw that question but it doesn't exist in the title of the thread or the initial post. He asked if IS helps in a given shooting sitaution and it does. Photographers with real-world experience have given examples when it does. You just can't admit you read something the OP didn't write.