But why?

To keep the dogs from smelling them, of course.

I'm also concerned. The only reason I can guess at would be to prevent data from being seized when going through a security crossing, such as when going from one country to another or into/out of a secured corporate facility.

Maybe we can be charitable and assume that the parent commenter did undercover work as a journalist/mule in an authoritarian regime, eg. bringing photos that North Korea didn't want to be public out of the country? They're not likely to let you leave with an encrypted uSD even if you claim you forgot the password. But the vast majority of reasons to employ such deception are more nefarious - either illegal corporate espionage or military espionage across an airgapped/monitored network, or distribution of CSAM.

Or maybe he just likes the taste of microSD cards?

I manage a fleet of over 1500 raspberry pis and sometimes put microsd cards in the same pocket I put my supplements and just scoop the pocket full and put it in my mouth and drink some water and swallow

After that happened once I did it again deliberately in front of some friends because it was funny

What do you do with 1500 raspberry pis?