Aren't Guardian's journalists full time employees? Why is their salary being paid by an outside entity?

Not the journalists. The "experts" they are interviewing.

Edit: I was wrong. The journalists are also part time and work elsewhere:

No, see the entire thread. They claim article author's salary is paid by some Coefficient Giving organisation.

	▲	graemep 2 days ago \| parent [-]
		I edited it before I saw this. Yes, and there is an article on the media influence funding too: https://www.effort.news/tarbell