Just pointing out the dangers. First thing I learned in chem lab was to never under any circumstances drink from a piece of lab ware. Even if it is brand new and outside of a lab setting. It’s the same as always assuming a firearm is loaded.
Steve, I understand you are pointing out what should be obvious dangers to most people that can read the back of a bottle of caustic because you are apparently very concerned for their safety.
In the context of this thread, the OP has proven to be quite capable of searching for MSDS sheets and understanding them. I'm very confident the OP or his keg tapping guests will not drink Draino from a beer line, even if he lets it in sit in the line for a year and gets Alzheimer's before the line is safely drained.
Before you say, "well I was just saying this for anyone who doesn't know" for the third time, please save your breath. They probably aren't here and hopefully the improbable minority heard you the first or second time.