LS 738 - given the name, they are clearly going to be biased towards Jet2, we know that, but there is little substance in the arguments.
the only thing they have correctly pointed out is that aircraft age is irrelevant, unless the delays are more frequent due to technical issues brought around by age, but that is something we cannot measure here.
regarding EU 261/2004 - age of fleet may come into this now as older aircraft "may" be more susceptible to technical issues through natural wear and tear and with that comes delays, with that, costs that Jet2 may struggle to fund if the delays are substantial throughout a season.