With the Filter object you have one rule per output, and everything that evaluates true is moved to this output. You can have new rules as you add new outputs, but you have to define all the conditions for every output in its correspondent rule.
I think the button New Rule is there because it is in the rules editor used in more operators, but it is grayed because you must add the rules adding outputs.
Juan's response is correct. The New Rule button is not operative with the Filter operator. To add additional output ports you click the Add Port button in the Output Ports grouping.
Once you have created multiple output ports, you can specify whether each incoming record will be emitted on all ports for which the corresponding conditional statement returns true, or only on the first port for which the statement is true.
For the use case you describe, you can put the entire statement into a single rule. There would be no need to set up a second and third rule. Simply add all three attributes as incoming rule parameters to a single rule and enter your statement.
Thanks for the the responses!
"you can put the entire statement into a single rule"
I'm not sure I know the syntax well enough. I've attempted different ways to filter on multiple criteria in a single rule, but I can't get it to filter correctly (or sometimes it just errors out). And, as comprehensive as help file is, I haven't seen where it covers complex rule statements like this.
If I missed something somewhere, or there is another resource I can look at, please let me know.