Anecdotally speaking, I have C-PTSD (and nearly all of its symptoms) and fit the requirements for BPD, including fears of abandonment and idealizing/devaluing that typically wouldn't be seen with C-PTSD alone. Both sets of symptoms cause me many problems, and I believe I need treatment for both, though my C-PTSD is way more severe than my BPD. I've read somewhere that the two disorders can have high co-occurrence rates in psychiatric settings, so given my own experience and what information I've gathered, I definitely wouldn't say that they're mutually exclusive, as in a person cannot have both.