Gartenberg said this is not based on concerns that robots such as Alexa could cause harm to humans. He is well aware that Siri and Cortana are just a set of speech recognition software and algorithms that can easily provide information such as weather forecasts.
However, someone asked Gartenberg if he would say "Thank you" to the bread machine or the ATM. Gartenberg said he will not speak loudly to the bread machine or ATM. When he asked Siri to turn on the lights or alert him, he would use the same natural language he used in his daily life. It's not important that Smart Voice Assistant can not hear or understand - what matters is what you say. If Alex does not say "please" when turning on the lights, will he do the same when he makes the same request to a roommate?
When he surveys people on Twitter, it seems that most people are not very polite to their digital assistants and they really can not differentiate between these differences.