iRule to mark VS status unavailable .

You could probably do this using monitors.

If you create a HTTPS monitor with the required Send and Retrieve Strings and then add in the Alias address and port of the HTTPS server.

Then create a FTP monitor, again with the required settings and add in the Alias address and port of the FTP server.

Then on the Pool, apply both monitors at the Pool level (rather then the Member level) and make sure the Availability Requirement setting is to to All.

I haven't tested this but think it would probably do what you need.