Is this “normal”, as my plastic surgeon puts it? (Photo)

You have a serious complication that needs attention by your surgeon.  It seems like you may need another opinion or doctor if your surgeon is not responding to this problem.MRSA needs to be eradicated before you start healing the open wounds.  You need to find a wound care clinic and let them assist your surgeon in your care.Dr Spies

Dear James'Girl1075,this type of wound is not uncommon after tummy tuck. It is usually caused by poor blood flow. I would suggest you to consult your plastic surgeon, follow your surgeon's instructions and keep your wound clean and covered. It can take few weeks or months for wound to fully heal. Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

I am sorry to hear about the complication you are experiencing.  The dark area  is an area of tissue that is experiencing decreased blood flow (necrosis).  It is hard to know whether the process involves superficial and/or deeper tissues.   
 These types of complications can be quite (understandably) distressing to patients;  unfortunately, sometimes the wounds do look worse before they begin to look better. The wounds tend to occur where incision lines come together (where there is the greatest tension and least blood supply).
Close follow up with your plastic surgeon will be very important; sometimes removal of a exposed suture and/or removal of any unhealthy tissue will expedite healing.  There may be different treatment modalities recommended; best to "stick with" your plastic surgeons recommendations. Generally, this will involve application of some type of sterile dressing ( in my practice I use a non-stick dressing covered by a sterile dressing once a wounded is clean).   
You should have peace of mind that these types of wound healing problems generally go on to heal over the course of the next several weeks, often without long-term sequelae. Also important to concentrate on a healthy diet, including good protein source.  Avoid nicotine. Sometimes (depending on the width of the open wound and the appearance of the scar in the longer term), scar revision surgery may be helpful down the line. Best wishes.