Regarding the remarkable points about AL-26,
"Meanwhile they were heating up, mainly from the radioactive element Aluminum-26. ... this hot stuff’s radioactivity is short-lived: With a half-life of 700,000 years, it was basically all used up, or extinct, within 2 or 3 million years."
So why was there a significant amount of it in the young Sun? Wiki[1] says it "is mainly produced in supernovas ejecting many radioactive nuclides in the interstellar medium." So are they guessing that the Sun condensed from a cloud of material that was _recently_ ejected by a supernova? (Because if it wasn't recently produced, there wouldn't have been any AL-26 left.) Something of a violation of the Mediocrity principle[2].