My world has creatures called "Puff Runners", which are theropod-like reptiles that have beaks rather than teeth, are armless or have tiny useless arms, and they mate for life.
One of the special things about "Puff Runners" is their distinctive gular pouch (similar to that of a frigatebird) which is covered in spikes (like a porcupinefish). Both male and female Puff Runners have them.
They don't use their gular pouch to attract mates but rather use them to especially protect their eggs and chicks (and sometimes in personal defense). First they intimidate the attacker by inflating the pouch, then they charge and ram them with their spiked gular pouch.
So my question: is my "Puff Runner" biologically plausible? Would they able to harm others without harming themselves?