I remember hearing/seeing that "he had the shits" that day, and wanted to wrap-up the scene so he can go recover/rest.

https://screenrant.com/indiana-jones-swordsman-shoot-raiders...

"It sounds wrong to say one should thank Ford’s sickness for one of the most iconic scenes, but Raiders of the Lost Ark is definitely better off for it."

https://screenrant.com/indiana-jones-raiders-lost-ark-gun-kn...

"A much more elaborate fight scene was planned, but Ford developed dysentery while filming in Morocco..."