Honestly, I wouldn’t let that one overzealous twitter user sway you one way or the other since that was really uncalled on both their ends despite their intentions. Plus we should focus on what our users want here and not what users want on Twitter and other social media. It’s good to spread the word and get some metrics, but don’t let it be the definitive answer.
With that said. I agree it seems more fitting to warn the user that it will merge all layers if it’s being saved as other than an ORA.
Also adding those Save As
PNG, JPEG ect. shortcuts that GIMP has in their file menu seem pretty useful.