To be clear, you can only be blocked by a user who is an Admin on specific wikis. They can tell/ask/request you don't talk to them on any wiki, but cannot *enforce* that other than to potentially report you for cross-wiki harassment.
They can NOT ban you from talking to them on Central about blocks they put against you because you're allowed to ask once for each instance. After that, they can ask you to leave them alone for that blocking incidence.
Of course, if you tick them off here on Central, they can increase your block if it is not already at infinite…
Also keep in mind that acting up on Central may bring the attention of the CCAdmins down on you…