I feel sure that Angie Bowie's participation in this year's CBB is by no means unconnected with the fact that David has been close to death for the past few months.
Her agent probably saw this as a one-off opportunity to get her on a show like this.
Whether or not they expected David to die while she was in there, they must have known it was a strong possibility, and from a purely showbiz/commercial point of view, it must seem like a dream come true.
Angie's own obvious lack of emotional connection with her ex-husband is probably understandable after so many decades apart, and given what her son has said about David turning him against her.
What I find more shocking than the farce surrounding the mix-up is the fact that absolutely no one in there seems to have been a David Bowie fan.
Nobody, including Angie, has expressed a word of regret or sadness (apart from Tiffany's faux-remorseful "I'm sorry for your loss"), or said anything about David's music meaning anything to them. Given their age-range, I find that quite strange.
Anyhow, I found the mix-up quite amusing. The fact that the entire episode is in the worst imaginable taste is just par for the course for Big Brother.