How was Scotty being an a** he was just a bit out of his time and behind on current engineering techniques and Geordi just had zero patience with him at all. I am a bit biased since Scotty is so awesome and yet Geordi is such a terrible engineer the Enterprise has a warp core problem everytime the wind blows.
Geordi was very patient at first.
Scotty got into things (he took apart panels and took out equipment parts), kept people from doing their jobs, snapped at people, got himself drunk and sat in a holographic simulator of the TOS Enterprise bridge. Being out of time and unfamiliar with 24th Century technology wouldn't excuse all that.
As a Starfleet Captain 80 years out of his time, he should have known better than fiddling with equipment in main engineering. He wouldn't have tolerated Trip fiddling around if he suddenly appeared during TOS' run either.
Scotty = Captain, LaForge = Lt. Cmdr. So at the very least LaForge should have treated Scotty with the respect his rank deserved.
"Captain Scott, I personally would love to be able to bring you upto speed on the latest technological advances. However I have an important assignment to complete so I'll assign one of my assitants Chief's to show you around."
Would have solved the problem, or he could have delegated the assignment to one of his assistants.