Bleach has its uses in home brewing, but I'd rinse it very well if used on any home-brewing equipment, regardless. Fit-for-purpose no-rinse sanitisers, specifically designed to target spoilage microbial communities, are not expensive, if used correctly. There's really no reason to be mixing up 5 gallons of sanitiser to sanitise an airlock. 1-2L is plenty for a 5 gallon FV, keg, etc, and it can be used to sanitise multiple items. Bleach isn't selective at all, it attacks organic molecules, especially proteins. Remember, wort is a complex organic media. And 99% of sanitising is actually cleaning before applying sanitisers.