But I didn't hand him the gun it was on the table If I handed it to him I for surely would have opened the action before
Regardless of handing it to him, you presented it to him for him to handle. In my mind, unless you just loaded a firearms for someone else to shoot, like a novice shooter, such presentation required that you had it over unloaded and action open. You are playing word/mind games by saying you did not hand it to him, when indeed you did present it for his inspection.
Not only that, you placed it on the table while your dad was busy talking to someone else. In other words you put it in front of him for him to look at while he was otherwise distracted. That was a very poor move, especially since you had it in the holster and he could not readily see if the action was open and it was unloaded from the look of what you wrote. I find that even worse than leaving it there in the holster. When you show a weapon to someone, they should have all their attention focussed on the weapon. Had he absent mindedly picked it up while talking, just out of simple reaction to your having placed it on the table, and then drawn it while talking - well yes he would have been at fault, but so too would you have been for allowing something like that to happen in the first place. Why fault, because whether loaded or not, the parties involved were not fully concentrated on what was being done.
Here is another what if - what if the other person in the conversation had picked it up? What if you all got so involved in the conversation because of interest, or emotion, that someone else like a child came by and picked it up, or your wife, or whomever. I am not saying this would happen but could happen becaus eof distraction of that ongoing conversation. You should have had patience and gun-sense enough to wait before showing it, or placing it in a position to be handled by someone other than you.
As for the whole dinner table thing, I almost cannot beleive you bring that up as some sort of defense for why you did what you did. It would have been best to first place a towel across the table. Then say woud you like to see the pistol now or wait until you finish your conversation. Chances are, you placing a towel across the table would have drawn sufficient attention to you for you to have made an announcement that you wanted to show the pistol then.
All just my opinion, based upon my own experience with brain farts and guns in the past.
All the best,
Glenn B