Start from there. Enjoy!
Didn’t hear the part about cereal?!?
Didn’t hear the part about snacks ALL SNACKS?!?
There are a few points here which you misunderstood.
First and foremost among them is that he was explaining reasoning to be lenient regarding coffee by being mitztaref together different opinions. This applies to bishul only and not pas.
One of those opinions is one that holds that a snack is by definition not OASM. According to this opinion, all snacks are not called OASM. This is not by any means agreed to by all. The Mechaber very specifically states that it does not need to be ללפת את הפת but rather even if it is לפרפרת it can be called OASM.
He never even said that all snacks are mutar as an actual psak.