Alderaan said:

You say you understand the emotions going on in the scene, but you didn't reference any.

Just because you don't read my posts it doesn't mean they don't exist...

http://originaltrilogy.com/forum/topic.cfm/Which-is-considered-canon-the-Special-Edition-or-GOUT/post/743033/#TopicPost743033

imperialscum said:

Before and at the beginning of the duel he is mainly enthusiastic to finally meet his son. When he disarms him and reveals the fact that he is his father he is excited and hyped up. After Luke turns him down he is utterly disappointed.

It is very natural in terms of father/son aspect. I see no reason what-so-ever for anger in this situation.