Saying "that person just is like that" doesn't justify what they did, at all.
Your actions have consequences.
You have to pay for your sins, and let me tell you, karma's a little bitch that may be waiting for you 'round the corner.
You have to realise that honesty can come out rude easily, but if you try at least a tiny bit, you'll be able to be honest and kind.
You know, life's unfair, but people make it 90% more unfair when they try to defend the people that shouldn't be defended for their shitty actions. If you do this, honestly you're as pathetic as them.
Anything, murder, bullying, rudeness, can't be justified like that.
Being rude just shows your low level that you're at.
No one can justify anyone just by saying "that's how they are".