That's exactly it. easyJet have three AOCs EZY/EZS/EUJ but one pan European unified branding. It's not as if Ryanair couldn't have used "Ryanair Buzz" or similar, the three Ryanair brandings are wholly disconnected. The race to keep
costs low is a known and long standing one, Norwegian also went down this path, but again, the Norwegian, Irish, Swedish and British AOCs had one unified branding.
Surely decoupling Buzz and Malta Air will have a sales and marketing cost.