His 12 years of college paid off.
Although he was concerned that there would be those in the church who would oppose his book on scriptural arguments, he didn’t seem that intimidated. He made it clear in his book that heliocentrism was a physical reality, not just a better math model of the planets. [The final person in charge of completing the publication (Osiander) did add an intro stating the work was hypothetical, to help avoid conflict, apparently.]
For about seven decades,
de Revolutionibus was never a big problem with the church. Galileo was key to causing the ruckus as he fought to introduce what is now called modern science. Had he realized just how much his ending pages to his
Discourse book were mocking his friend the Pope, Galileo likely would have avoided the harsh treatment he later received from him.