First, it won't be poisonous. Assume two ounces, even four ounces spilled into the brew. At 1 tsp of bleach per gallon of water, you've spilled 1/32 of a tsp of bleach into five gallons of beer. My household bleach is 6% sodium hypochlorite. That's 60,000 ppm straight. You've diluted it by . . . 128 ounces, 6 tsps/ounce, so 768 fold? So your sanitizing solution is now about 78 ppm. You've further diluted that by a lot - 5 gallons, 128 oz/gallon, 640 ounces. If you added 4 ounces, that's 312 parts added, so you're down to less than 0.5 ppm. Drinking water typically has 2-3 ppm chlorine - so definitely not poisonous.

Will it be ruined? Maybe, but I don't think so. The taste threshold for chlorophenols should be much higher than 0.5 ppm.

Will it inhibit the yeast? No. You can make a beer with straight, unfiltered, chlorinated tap water, and the yeast will not be inhibited.

All of this assumes of course that my math is right - I think it is though, but if I've screwed something up someone tell me!