"common sense" is common sense because it is the "sound and prudent judgment based on a simple perception of the situation or facts" (1).

Maybe what you meant to say is that the position isn't, in fact, "common sense", that it is neither sound or prudent?

(1) https://www.merriam-webster.com/dictionary/common%20sense

Keyword being "simple". The common sense solution often turns out to be unsound based on a more detailed perception of the situation

Oh yes, "sound" and "prudent" haven't been in the ballpark nearly as often as they used to be :(

The dictionary definition is in spite of the fact that the phrase "common sense" is more often than ever being used to rebrand what was formerly known as "common lack of sense".

They wouldn't say it if it wasn't false :\