I don’t think anyone has suggested that easy can provide all the Islands air travel needs. By the same token, I don’t think a semi frequent, regional aircraft operation can either. The two co-existing is a win win in my opinion.
As for overnighting, it’s not beyond the realms of possibility. Pre-pandemic, easyJet overnighted several LGW aircraft at various stations including INV. That said, the arrival by 9am need is not as big as it once was and the pandemic will impact this further. I’m not saying it isn’t there but I’m sure that market will be well catered by the small aircraft operator at the corresponding fares.