Well, yes, that is a difficulty with the hypothesis if the earth-sun mass relation is correct as it currently stands. Heavier elements in the sun would then result in a few thousands planets like earth. The author contest the relationship while myself, I have not reached a conclusive opinion on that. I can't say until I understand much better than I do what mass and gravity is.
Anyway, the current understanding of what drives the sun and other stars and how exactly is not the last word to be spoken to be sure. What though I have no doubt about is that the whole big bunk framework to stellar and planet formation is definitely pure fancy and will be completely abandoned in a few decades from now. Whatever is the case, the Sun is not the second or third generation of stars in existence. The scenario where the Milky Way is as old as the existence itself is certainly all the way off. One might be much older than currently estimated, the other may be incompatible in principle with the idea of measurable age.
The current figure for a single spin of the galaxy is 250 million of years. Spinning is how it has got its into its present shape. Forty odd spins all in all is extremely unlikely, methinks.
Edited by Alfred Maddenstein, : grammar