I believe the job description was "undercover narcotics."
No, of course you or I wouldn't do it. He did. Part and parcel of the persona he adopted for the character he played interacting with others who were not gun savvy. It looks stupid, but it works, so maybe it's not stupid. The gun wasn't meant for range use, and he apparently did it for some time and got used to the quirks.
We ALL drove around with people in the back of pickups in the day. I was one of those who was in the back, in 20 degree weather, going 25 miles in the wee hours of the morning to go deer hunting. When we stopped I started warming up for a full day's hunting. I didn't die in the attempt, it's what we had for transportation and it worked. You also learned not to put your hand between the cab and bed or it got pinched.
What we did then was within the acceptance levels of risk for the time, just the same as putting half a dozen kids in, and for the most part - 99% or better - no one got hurt. Its the safety mavens who dictated that it should stop. I won't argue the point, but no grips on your 1911 is your business. We have some who practice on a range with appendix holster, some who pocket carry without a pocket holster, some who carry .32's, where do you draw your line? It's your business.
Once you let it get to the point of regulation it becomes public business and then then from that time on it's a matter of revenue. Usually more tickets handed out than actual injury. We start letting society dictate it's collective sense of what is safe.
At that point, they try to ban the carrying of firearms anywhere, which ones you can have, what calibers, the sale of military surplus, because you aren't professional enough to use them.
I suppose the next thing in pickup regulation will be a certification you know what and how to load the bed correctly?
Don't take the intrusion of other people's sense of safety as an absolute. It may not fit your requirements, and it does contribute to the growning restrictions in liberty.
Carry no grips all you want. Just be aware of the consequences, and it's your free choice.