If a person were to be opening a door expecting a trap like that and someone bursted through the door like that, they would almost certainly at least have the gun pointed at the person no matter who they are; if the person has any amount of training, their reactions would probably take over and end up shooting the person. So at the very least, that tension of him almost but not shooting probably should be there if the goal is for any realism in his actions. But I would also agree that I don't know of any reason anyone would ever grab both weapons like e pointed out.
To add to what Awaclus described, when walking and looking around, the arm with the gun should be bent up where it is in front of your chest with the barrel pointed at the ground in front of you (finger off the trigger, extended along the side of the barrel), so that when you aim, you aren't having to raise your arm from your side, but rather are just extending it straight in a line away from your body to the target
like the gentleman in the picture, except the off hand will be holding a bat I guess.
When/if you aim, hold the gun with your wrist at a slight natural angle inward, like between 20-35 degrees from straight verticle. Some might not do this or have likely never heard of this, but that is a more natural position to be able to lock your wrist in place to control the recoil better when having to shoot 1 handed. This is a slight detail that probably 99% of people wouldn't catch in a movie though, because as long as your stance and basic gun safety is good, even most gun enthusiasts wouldn't pay that much attention to details like that in a movie.
Most importantly though, just don't hold it horizontally movie gangster style. It's just wrong.
(link above is to a random concealed carry training website that just so happens to have the best pic of what I was describing that I could find)
edit: typo