In your brother's particular situation, it's likely that he said that and may actually follow through with that simply because he refuses to admit any wrong doing that led up to HIM being kicked out. First off, he is 25 years old. He should have had some money saved up and at least had the self-motivation to live on his own by that point in his life. For example, I had my own place when I was 19 & have never had roomates.
Secondly, I highly doubt that he was doing his share of chores and being considerate of others in the household for it to come down to his father kicking him out. If a child of any age lives under the same roof as their parents, the bottom line is the parents "rule the roost."
Did your brother graduate with a degree already and was simply home looking for work? Is he working on another degree & out for most of the summer? What is he doing with his life to have been at home at 25 and even be under the threat of getting kicked out? Surely he was not doing as he should have been.
Your brother clearly did not do as he should have and got what was coming to him. To save his ego/face, your brother acts as if he was wronged. Many people do this but it doesn't make it right. I don't even know your father or the things that led up to this but would be highly willing to say your father put up with a lot of crap before he had to stand his ground and kick your 25 year old brother out.