Right, but if you had signed a CLA then it's absolutely not violating the AGPL if the host decides to close the source. Since these organisations require that,

Right, but if you had signed a CLA then it's absolutely not violating the AGPL if the host decides to close the source. Since these organisations require that, they're not violating the AGPL. That's not to say I agree with them and it's obviously shitty behaviour – but license violation is a specific act that they aren't guilty of.