I'm going to throw out a possibly unpopular opinion, because I have a feeling this is exactly what was going on at my old workplace.
What is the gender of the 4 employees who have a problem with the senior SDE?
At my workplace I was the only female employee and when I ever had complaints against someone for being condescending/etc the response was similar to yours, "But I never had that experience with him. He's a nice guy."
Understand that you only see one side of your senior dev. You don't get to see how he interacts with women or other minorities.
An example I like to give is that even Senator Obama experienced people being fearful and locking their cars when he went out to the parking lot late at night. That's an experience that white people just don't have, and imagine being the only one to experience that or report that in a group of other people who have never ever been the target of such behavior. "But I never noticed it!"
If this does turn out to be the case I'd suggest you have a serious chat about diversity in your company. I ended up leaving tech due to my similar experience in my last company. Saying, "We're pretty diverse for a group of white dudes" isn't enough. Listen to the minorities at your company and their experiences and don't invalidate them or dismiss them because you haven't experienced it. You could learn a lot and save some people from leaving the industry.
What is the gender of the 4 employees who have a problem with the senior SDE?
At my workplace I was the only female employee and when I ever had complaints against someone for being condescending/etc the response was similar to yours, "But I never had that experience with him. He's a nice guy."
Understand that you only see one side of your senior dev. You don't get to see how he interacts with women or other minorities.
An example I like to give is that even Senator Obama experienced people being fearful and locking their cars when he went out to the parking lot late at night. That's an experience that white people just don't have, and imagine being the only one to experience that or report that in a group of other people who have never ever been the target of such behavior. "But I never noticed it!"
If this does turn out to be the case I'd suggest you have a serious chat about diversity in your company. I ended up leaving tech due to my similar experience in my last company. Saying, "We're pretty diverse for a group of white dudes" isn't enough. Listen to the minorities at your company and their experiences and don't invalidate them or dismiss them because you haven't experienced it. You could learn a lot and save some people from leaving the industry.