No. The advantage will be for folk making connecting flights and for those affected by delays. Someone who travels with AUR and misses their EZY flight (and has booked in this way) will be put on the next available.
EZY will still be EZY just as AUR will still be AUR. The earlier comparison between the village shop and Tesco is a good one. Look at aircraft utilization. One ATR72 can operate four returns in a day from GCI - to Manchester, Bristol, Stansted, and Manchester. However AUR often split the operation with one ATR doing Manchester and Bristol, with the other doing Stansted and Manchester. An ATR can thus be sitting on the tarmac at GCI for hours on end. Not economic sense perhaps, but at least back-up is there in case of another aircraft being u/s or fog descending.
Put together the EMB195, three ATR72s and one ATR42: you have 5 aircraft. One is regularly acting as a spare out of the five. EZY have a fleet of 279 Airbuses. If 20% were spare every day there would be about 55 Airbuses not flying! No, you can't compare the two outfits; just as chalk and cheese and Tesco and the village shop are different. It's unfair for anyone to try and put AUR in the low-cost league. But at least there is local commitment and they make a genuine attempt to get their pax home to Guernsey at the end of every day.