The ex-G4S employee, 35, terrified Glasgow hotel guest Stephanie O'Brien, 23, after confronting her with the apparatus, claiming a fire had been reported, on November 4 last year. She was fortunate to escape unhurt.
On November 13, the wife-beater, who became enraged when women contradicted him, killed Thai-born Ms Satjawat in the toilets of the Clyde Auditorium, part of the Scottish Exhibition and Conference Centre (SECC) where he worked.
She had merely questioned why he needed to check her security pass again.
Carter, of Motherwell, North Lanarkshire, was sentenced to a minimum of 20 years in prison after he was jailed yesterday for life after being convicted of Ms Satjawat's murder at the High Court in Glasgow.
During her evidence his wife Paula admitted her husband could be violent and had once strangled her.
Mr Carter was also found guilty of a breach of the peace for the earlier hotel incident. The trial judge, Lord Matthews, wondered in court whether Miss O'Brien was lucky to be alive.
It emerged during the trial that Ms O'Brien had tried to tell staff at the Holiday Inn Express in Stockwell Street what had happened. But she said she was made to feel "really silly", the court heard. She made no formal complaint.
Neither the police or Carter's employers G4S were informed about the incident.
Nobody attempted to contact the Security Industry Authority, which would have had powers to suspend his licence if he was under investigation.
Instead, he was on duty at the SECC to kill Ms Satjawat, who was attending an HIV conference. Only when police began probing the murder did they discover the earlier incident at the hotel. His licence was then suspended.
Jan MacLeod, co-ordinator of the Glasgow-based Women's Support Project said: "It is disappointing this opportunity was missed. People should learn to listen and be empowered to listen to women who are upset. They will usually have a good reason."
Heather Coady of Scottish Women's Aid said: "Dismissing a woman's account of a fearful and dangerous situation and writing it off as exaggerated, hysterical or vindictive is seriously misguided and can have horrific consequences as borne out by this case.
"Training should be standard practice for hotel staff and be underpinned by workplace policies that staff can refer to where they are witness to or aware of any threatening behaviour or assaults experienced by female customers.
"They should be equipped to deal sensitively and appropriately to fears and concerns that may be expressed by their customers. If this is not in place then it's hard to see how hotels can be safe places for women to stay."
Ms O'Brien, of Cumbria, who was staying with friends, had asked for help with a stuck zip on her skirt. Carter, who was on a shift as a security guard, tried to help but broke it. Carter then knocked on her door after her friends left, holding the extinguisher. He claimed there was a fire in her room.
She told the trial: "I froze at the door, terrified. I thought 'I need to get out this room and not turn my back on him'. He came towards me and I ran back in to the room. I ran right past him in to the room and locked the door."
She then sat with her friends in the bar. Carter was also in the room, but she said staff dismissed her concerns.
A G4S spokesman said: "I can confirm the Holiday Inn Express incident was not reported to us."
Holiday Inn Express on Stockwell Street is owned and operated by Somerston Hotels (Glasgow) Limited, under a franchise agreement with InterContinental Hotels Group (IHG).
A spokeswoman for IHG said: "While IHG works closely with our owners to ensure procedures and practices are in place to safeguard and protect guests, IHG does not employ the staff at the hotel nor its contractors. We have no evidence to suggest staff behaved other than in an appropriate way in response to the facts."