The time you spend after death in the spawn selection screen should be deducted from the time needed to spawn on a CRU or drop uplink. If I spend 8 seconds in that screen, and select a CRU as my spawn point, I should only have to wait 2 seconds (meaning you wait 10 seconds total), and if that CRU becomes unavailable, you won't have to wait another 10 second when you pick another spawn point.
Other example (just in case someone doesn't get it): You've been in the spawn screen for 12 seconds, you select to spawn on a drop uplink that requires a 20 second wait, because you already waited 12 seconds, you only have to wait 8 more seconds (12seconds + 8 seconds = 20 seconds total). If 4 seconds passes after you selected the drop uplink as a spawn point and the drop uplink is destroyed (which cancels your spawn), if you choose another drop uplink with a 20 second wait time, you should only have to wait 4 seconds to spawn on the new drop uplinks (spent 12 seconds before picking a spawn point, 4 seconds waiting to spawn on the first drop uplink, this all totals to 16 seconds out of 20, leaving only 4 more seconds to wait). If after the first drop uplink was destroyed, you picked a CRU to spawn on (10 second time), you shouldn't have to wait at all to spawn since you already spent 16 seconds.