It does say "Troops", but it does seem a bit mental that they would leave their Leader behind? ... or does it!?!?!I thought the same but consider Bene Tleilaxu Gholas ability: you need to pay Spice for each "resurrection", with Spacing Guild's special ability symbol, you could resurrect and reuse your leader again and again the same turn (if multiple combats await you).
The ability might rescue the leader as well but only if a statement was added: "you cannot use a leader evacuated this way again during this turn" or something similar. Otherwise, wouldn't the ability be too strong?
EDIT: On the other hand, paying Spice for Gholas is not that big of a deal and you don't need the special ability symbol for that...