I saw RMS give a talk once on Free Software. He wore three quarter length cargo pants and sandals with no socks, and spent a good amount of the talk picking a scab off his shin to the point where he started bleeding. It got on his fingers. No one said anything.

There are things in this world that people can and should be stopped from doing, and there which anyone can do unhindered if they so wish. In between those two boundaries there’s a standard of decent behavior that one should strive for in order to be considered a good person.

Giving credit isn’t required, but many consider it basic decency.

Stallman famously ate something off his foot during a lecture, on camera https://www.youtube.com/watch?v=I25UeVXrEHQ

OTOH I'm not seeing the problem with scraping a scab. I have hands, my attention is focused on something, then my hands will scrape where it itches (the scab).