That's where the confusion / misconception is I think. The concept of BA Flights is in relation to the Bronze and Silver levels where you can do 25 or 50 BA Flights to get to this level.

BA flights is then subsequently defined as
-flights operated by British Airways, including franchises and BA CityFlyer
-codeshare flights on other carriers with a BA flight number
-flights operated by Iberia, including franchises, with an IB flight number

However, to get to Gold, seems like there is a requirement to fly on BA metal (and marketed) 4 times.

But as another poster said, maybe in practice, IB flights do seem to count towards the 4 BA flights quota.

Seems like this program is marginal for me.