Instead, the 39-year-old, who uses crutches and a wheelchair, was confronted by a thug who forced him to hand over his wallet, watch and mobile.
The callous robber even snatched the sunglasses off his face but when Stuart finally struck back with a blow from his crutch, the suspect stabbed him in the cheek, leaving him requiring 23 stitches.
Detectives described the robbery, which took place at around 12.50pm on Thursday, as “despicable”.
Speaking at his home, Mr Gunn said: “I was getting ready to go out and meet my father for lunch. The doorbell went and I thought it was the postman with Christmas parcels I bought online.
“As I opened the door, the first thing that hit me was the strong smell of stale body odour, alcohol and cigarettes from this man.
“The next thing I knew he had put a knife to my throat. He started demanding my wallet which was hanging from my pocket on a chain. Then he spotted a watch on my wrist. He tried to grab it but he couldn’t work the clasp so I took it off. He also took my phone and snatched my sunglasses off my face.
“He kept pressing the knife harder and harder against my throat as he made demands. It eventually broke the skin.
“Then he used a derogatory remark about my disability. That’s when the fury about what was happening to me came out. I lashed out at him with my crutch. My right side is paralysed so I tried to kick him with my left leg.
“I felt what I thought was a punch to my face. I was off balance and fell to the ground and he ran off. When I felt my face it was wet with blood running down on to my neck.”
Mr Gunn, who has been paralysed down his right-hand side for ten years following a motorcycle accident in 2002, added: “I don’t know if I was deliberately targeted. My door is the first one as you come into the building so it may have been chance.”
Mr Gunn, who also suffered a seizure five years ago which saw him lose his vision, returned to his flat and used an emergency alarm connected to council workers who called for police and an ambulance.
The suspect is described as being around 5ft 10in tall with a slim build, in his mid-20s or early 30s with a local accent.
Detective Sergeant Dave Pinkney, who is leading the inquiry, said: “This was a despicable and opportunistic theft, which targeted a vulnerable man who was virtually unable to defend himself.”
Det Sgt Pinkney said that CCTV showed Broughton Road was “very busy” on Thursday lunchtime as he appealed for witnesses to come forward.
Richard Hamer, director of external affairs at Capability Scotland, said: “It is vital that the police target significant resources at catching the attacker to prevent further such robberies and to reassure Edinburgh’s disabled community.”