Lawyers can say such things and I'm sure that Facebook will try to fight it, but I don't think they'll be able to do so successfully, because the GDPR is very specific about what a "legitimate interest" is.
PS: the EU can't wait to give fat fines to companies like Facebook and Google, due to their tax evasion schemes. It's the whole reason for why these companies haven't been able to stop GDPR, with all of their lobbying prowess. And I don't care about such motives, as an EU citizen I'm glad that GDPR exists.
See here for an explanation: https://www.gdpreu.org/the-regulation/key-concepts/legitimat...
PS: the EU can't wait to give fat fines to companies like Facebook and Google, due to their tax evasion schemes. It's the whole reason for why these companies haven't been able to stop GDPR, with all of their lobbying prowess. And I don't care about such motives, as an EU citizen I'm glad that GDPR exists.