There were intelligent people back in the 1910's too. Some were just as intelligent as any born today.
In real life, stripped bare, a 20th century man transplanted to the 25th century would probably be just as able as a 21st century man.
What's a joke is assuming that a 20th century man would act like one of the Three Stooges.
How is a radioactive gas supposed to put someone in suspended animation? it doesn't make physical sense, at least when you freeze somebody their molecules slow down. I don't know under what circumstance a World War I fighter can get in perfect suspended animation by accident. A more plausible story line is an astronaut in the near future freezes himself deliberately.
That's just the popular Phlebotinum of the era. Today it would probably be nanites or something.
The point is you have a modern man with some sort of interesting life history get frozen in time. Say what you want about WWI biplanes, those pilots were badass. They took to the skies in new technology to duel to the death (sometimes with pistols). Same deal with an airship pilot. A man who sailed the skies like a "futuristic" sailor. An average 1950s man was born in the depression and fought WWII.
Today, it could be an Air National Guard pilot who works for a biotech company full time.