Sure, maybe they can evict the horde but the damage is done. Those officers have been pulled and killed since they go down easily. SHB is pretty much as close to IBGY as SHGY so once the horde are in there you have trouble getting them out before they cap it.
Now you’re pushing back-and-forth in the mid and the horde is already ahead in points. Sure, maybe you can push them back to IBGY but then that superior choke makes it difficult to push any further.
In the end there are certainly further problems since that bit of a head start shouldn’t cause the alliance to lose nearly all battles. You’d expect the horde to capture a few more wins because of it but not all of them. But all possible imbalances should be tackled and map differences are the easiest: switch up the starts randomly.
Then we can look to thornier and more complex issues to address.
The alliance definitely should not take it. Then people dying will be split between SFGY and SHGY which will make it easier for each group to be killed by a concentrated force. Also, this will ease up on the choke at SHGY and basically give SHGY to the horde as well as let them past to get further northern objectives. Now it’s a race and the horde have a big head start.
Although it would be good if there was enough coordination to not only take SFGY and SHGY to double up on rezzing but also use that to push hard. Each group should head towards each other and link up before heading south. That way they could use their higher numbers to push past the defender south. Still, it will be tricky to do this and hold both gy, as well as defend against people heading north.