Long time lurker and first post, so bear with my minimal use of abbreviations, codes, acronyms!

So, my partner and I are flying Sydney to Tokyo on QF021, on an economy sale fare (Q). After selecting our seats when we made the booking, I went back the other day and noticed I could select what seatguru would indicate as a premium economy seat. Went back today and now it looks like I can select business class seats (30J, 30K). I'm pretty sure I'm matching up the seat maps correctly but I didn't think upgrades would come through via your seat selection options?

Does this seem too good to be true?

I'm 100 points short of platinum if that would make a difference?

Thanks in advance.