PhD expectations of commitment I was discussing the possibility of entering a PhD program from a professor who I had during my masters degree.

We discussed the level of commitment he expected and he stated he expects PhD students to be committed to PhD completion above all else, regardless of subject interest or circumstances on the part of the student. Basically he wanted someone who would 100% be his yes-man. 

While I made clear I had a strong interest in the subject(and my prior performance in these areas is reasonably good) I couldn't say without actually entering the program what the result would be. Communicating anything else felt dishonest, basically I had a strong belief but I couldn't make a promise. 

Is this position standard for PhD advisors? Basically, is it reasonable to assume someone will be 100% committed to something without experience working on the problem?
My personal assessment is that the professor is correct. A good PhD student in my opinion is someone who is committed fully to the completion of the thesis, and spends 100% of working hours (and let's face it, even much beyond that) on it. There is no way around it, if one wishes to be a good academic. 

Also:
"expects PhD students to be committed to PhD completion above all else, regardless of subject interest or circumstances on the part of the student. Basically he wanted someone who would 100% be his yes-man."

My impression is that the premise of the sentence does not imply anything about being a yes man. It simply means full dedication. 

Following clarifications, the Professor did insinuate the candidate he/she should be a yes-man. This is a warning sign, and is unrelated to the question of dedication needed to complete a PhD thesis.