Boy, you have a tall just turned three year old!
If he meets the height requirement, its up to you. We have ridden one height requirement ride with our 4 and 5 year old (Body Wars) but that is for a whole lot of reasons (my husband doesn't like thrill rides, my kids were happy with the rides they were on, I'm in no hurry to have them grow up, we were traveling with Grandma, my daughter was just 40 inches and had suffered a mild concussion the day before we left and had instructions to take it easy for the first few days).
I haven't riden Kali, but have been on similar rides at other parks and can't imagine Kali being much rougher. But it is VERY WET. If your three year old doesn't like water dumped on his head (mine didn't at that age), avoid the ride. If it is chilly out, avoid the ride.