I would call and ask. It is not like Schizophrenia, it should be easier to get approval on this. It all depends on the APS, underwriters mood and so on. MS and HIV positive are much more severe than this disease and they can now get underwritten by some carriers.
You're kind of simplifying and generalizing with the comparisons to MS and HIV. MS can be dormant for years or decades with or without treatment (and it can be argued the larger risk with MS is suicide). And HIV is only recently become an issue insurers are comfortable addressing because it has enough track record that we can try to frame some mortality.
Saying this is simply a personality disorder doesn't take in that there are schizophrenic features. Personality disorders are already murky enough to underwrite without throwing in major features. The reason issues like bipolar get hard to place isn't the episodes they experience; it's the 200-250% higher suicide rate compared to the normsl population. In schizophrenia suffers the attempts are put at around 40%, younger people with it are around 50% (about 400% higher). Even if it's in the conversation it's not something to be taken lightly.