Could Force Z join the surviving American fleet?

Could Admiral Phillips send Force Z to link up with the American survivors?

Potentially, but it would depend on where the battle occurred and how much of the American fleet survived in fighting condition.

Ships sunk in deep water are permanently lost, unlike the recoverable wrecks at Pearl Harbor. On the other hand, maneuver, concentrated fire, and fleet formation improve the odds that individual ships avoid hits. The strength, location, fuel state, and remaining air cover of the survivors would determine whether Admiral Tom Phillips could usefully combine Force Z with them. A linkup could reinforce the Allied battle line, but it would be a response to the actual losses and strategic situation rather than an automatic next step.