oh, man. this stuff gets confusing...

lets remember:
You only win if you are at least 1 second faster for any team, be that att1 or att2.
AND
In the scenarion 2: Attackers 1 fail to plant + Attackers 2 plant at 14:30 = DRAW
this only says that defenders 1 WERE able to make it easier to at least Draw a match. that is: THEY are less likely to loose, because they WERE GOOD AT DEFENCE at round1. it is not more difficult for them to win - the same rule of 'be faster than opponent' applies.
to be clear. lets imagine a map with 1 objective. IF attackers fail to plant IT IS ALREADY AT LEAST DRAW. attacker2 cannot loose this already.

tldr;
i disagree, that these 2 scenarios favour attackers1 because each team still has to be faster than another.