I don't know where you last got your information about Epita, but this has been less and less true for around 10 years now.
They sought to have a state certified engineering degree for a long time and implemented a lot of changes around 2003-2007 that made the cursus a bit less about code a more about common engineering stuff (maths, physics, english, ...) with more structure (they structured classes with a credit system, made more standard student evaluations, ...)
Source: graduated in that era, been in touch with later students.
Even if it's true that Epitech us mainly about coding, the program enforce a coding standard that is a huge part of the final grade of each coding project (small functions, 80 char per line of code...). Fom the second year, components decoupling and basic design patterns are part of the program.
Nevertheless, the school doesn't really make the most to teach basic good engineering practices or at least I don't remember (doc, tests, vendoring, observability...) and this is one of the main pain point.
Niel did not come from the traditional path of the elites (Polytechnique Paris, Centrale, etc.).
He was self taught, and god forbid, earned money through minitel porn. The aristocracy considers him, well, gross.
Their CVs should be findable on the public internet.
Yeah, no. 42 was modeled on Epitech. If EPITA was about "code, code, code", why did Sadirac leave and founded Epitech and 42 ?
Also, while it's nice that Xavier Niel finances a school that is free, most of the universities and Grandes Ecoles (where many developers graduate from) are also free, and financed with public money. They work great and produce really skilled developers and architects.
The reality is that Xavier Niel didn't do a Grandes Ecoles, he's mostly self-taught. When he started to succeed in the telecom industry other companies, full of alumni from Grandes Ecoles didn't see him with a good eye because he didn't have the pedigree (and didn't hire many of them either). So he has a grudge about the Grandes Ecoles system, and creating a school with private money is kind of a middle finger to them.