So even though this says it was Everton that pulled out, they were still going to play behind closed doors but City of Liverpool said no
Everton did pull out. The behind closed doors was an alternative option which CoL decided not to take. Absolutely no benefit to CoL to play a scratch Everton U23/U18s side behind closed doors after the severe financial losses incurred at that level.
I don't know but they may well have to demonstrate their ability to handle and police gradual increases in crowd numbers to satisfy Covid regulations and don't want to disrupt that with their eyes on the new league season starting.
I'm no fan of "The Purps" but it's an entirely sensible thing to do.