On the contrary, being so entitled that you think you deserve other peoples' initiation is selfish. You might have the impulse to spout to other people, but a lot of people don't, and they just do their job. Why isn't the other coworker rude for not making small talk for 2 weeks? Why isn't it that the other coworker is only making "small talk" to (insulting) someone else to make themselves feel better?