When the author says that Persona claims the "legitimate interest" basis for these data, they're saying that Persona is trying to achieve maximum flexibility for using the data (since "consent" generally requires specific agreement on a specific use for the data, and the burden of maintaining the consent records, where "legitimate interest" does not).
https://www.bulletproof.co.uk/blog/consent-vs-legitimate-int...
This is where I disagree. You basically have to use LinkedIn to participate in today’s job market. These large platforms that are protected by network effects should be highly regulated so they cannot abuse your privacy and rights.
In many companies, you don’t need to bother applying without a LinkedIn profile. You’re not even going to be considered for a position, full stop.