My masks, which specifically fit well and seal well, are like all masks made by design standards hard to breathe through, and they often collapse and inflate as I breathe, especially when riding my bicycle.  

I have never seen a mask with leakage around the edge have this problem; those are worthless, but very easy to breathe through!

I am wondering if this is what the author meant to say   Perhaps he meant that if it is possible for air to leak around the mask that would force air to come in around the edges of the mask.    But how would it by itself indicate air leakage?   It seems pretty clear it just indicates a high efficiency mask that is hard to breathe through!

Only N95 masks are both effective and easy to breathe through.  Two layers of properly dense fabric never will be.

Yours,
Dora Smith