Bollocks? Maybe. I don't know as I don't fly those. Just first hand info from a Qatari skipper that I took at face value. I shouldn't have taken it as gospel.
It's not comparing like models really, is it? A350-9 vs B777-3ER ~ 65tonne difference. Many variants of the RR Trent WXB engine & I believe they utilise the 84000lb model. Maybe someone actually there (QR) can elaborate on what I was told?
Anyway, back on topic, good luck on the new Canberra run, which is good for Sydney punters with more seats available, especially during holiday/peak periods. Also good for Canberra with another International global network connection. Private owners may have to put in more airbridges, the way they're going
Happy Landings.