Clearly he is complelty frei since after aleinu every siddur has the ani maamins and shiesh zechiros therefore they must be integral parts of shacharis too I’m not sure why he indicates it would be ever ok to skip it.
For the benefit of Okiale, who may not be familiar with the style of various posters here, I will point out that ubiquitin is exaggerating here when he calls theprof1 completely frei (irreligious).
His point, I believe, is that not everything printed in the siddur is a requirement to be said, and it is a correct one.