No is correct, but Uptime can be used to determine this role amongst Unleashed APs.
If the APs all stay up, your role assignments should not change. So one workaround
if some APs have unreliable WAN links or suspect Eth cabling, woudl be to reboot them
occasionally, and they won't have longest uptimes.
But, failover/maintenance is important to the Unleashed solution. Since all member APs
(from Standby Master to just other Members) are ALL updated with the configuration
details to step into Master AP role, you can always connect wirelessly to your Unleashed
PSK WLAN, and use the 'unleashed.ruckuswireless.com' URL to access the current
Master AP, so you should feel comfortable knowing that your wireless network is designed
with built-in recovery mechanisms.
Your question/suggestion for Excluding an AP from Master/Standby Master role, (if there exist
two APs in those roles already), due to uncertainty about their availability, would be an Unleashed
Feature Request and would need to be submitted by your local VAR or Ruckus Systems engineer
(thru a support ticket) for our Product Marketing team to consider.