Ginbey was struck on the back of his hand by the lemon just moments after the club's 30-point win over Essendon a fortnight ago.
The lemon flew about 30m in the air before hitting Ginbey, who last week expressed his shock at the incident and said it was fortunate it didn't hit him in the head or the eye.
Vision showed the thrower also had a second lemon in his hands, which he didnt use.
The fan, who was not a West Coast or Essendon member, has copped a five-year ban from all AFL and AFLW games.
"You can't do that, so I think it's the right decision," McQualter said on Thursday.
"We've got to protect our players."
Ginbey could miss the rest of the season after tearing his left quad during last week's six-point loss to Port Adelaide.
The 21-year-old is West Coast's best defender and McQualter is backing his team defence and pressure further up the field to help cover the loss of Ginbey, who recently signed a contract extension.
West Coast face North Melbourne at Optus Stadium on Saturday, meaning there will be plenty of heat on key backmen Tylar Young and Rhett Bazzo to contain the likes of Nick Larkey, Jack Darling and Cooper Trembath.
The Eagles lost No.1 draft pick Willem Duursma (calf) and Tom McCarthy (hamstring) to injury, while Malakai Champion was dropped.
West Coast have handed a debut to mid-season signing Marcus Herbert, while Tom Gross, Elijah Hewett and Josh Lindsay all earned recalls.
North ruckman Taylor Goad, a first-round draft pick in 2023, has been named for his AFL debut, with Cooper Harvey and Tom Blamires also joining him in the side.
Riley Hardeman is out with concussion, while Wil Dawson and Zac Fisher were dropped.
McQualter is expecting North to come out breathing fire after they copped a 124-point thrashing by Fremantle in Bunbury last week.
The Kangaroos were held scoreless in the second half as the Dockers piled on 19 consecutive goals to post the club's biggest-ever win.
"We've done like a little bit of research around every time they've had a loss this year, maybe a bad loss, the way they've turned up the next week has been really quite fierce," McQualter said.
"So that's what our expectation is - they'll turn up.
"Every player has pride in performance and team and I'm sure they'd be disappointed with their game last week.
"But the expectation is that we'll get a red-hot Kangaroos turn up on Saturday afternoon."
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