I can see exactly why you feel that what the LDDLG did in the circumstance you describe was unfair. I can also see myself thinking it was unfair if I was there, and would have likely 'requested' that they assist you.
However. And its a big however. We as the Brotherhood only want peace between the corsair factions. If you wish not to help each other, it isn't up to us to force you to. This goes for both the LDDLG and the SCRA. All we ask is that you do not shoot each other. We do not set boundaries forcing you to actively help each other, even in the defense of Gamma.
Contrary to this though, we do expect at least some common sense from those that inhabit Gamma and keep it safe from intruders. However, the line where this can be drawn is hazy at best, and invisible at worst. A line in the sand is not solid, and can be washed away by a single wave.
I am sure the LDDLG would defend Crete from attack, as they were training above it. I think the problem lies in them not attempting to defend you. It is legitimate on their part, whether you or I like it or not. It is most unfortunate though, as it shows that only both sides respect to the wishes of the Brotherhood is keeping you two from tearing each other to pieces...
Understand, it is a lot harder to deal with group's lack of action, than to deal with those groups actions themselves. This is because, technically, they did nothing wrong, as they conducted no actions. I cannot stop a mutual hatred between your two factions, but I will stop violence.
Your complaints put me in a very odd place Ares. I would appreciate it a lot if you could contain the anger that runs through the blood of all Corsairs, including myself. I have to be learned in diplomacy, even though it is against the Brotherhood's philosophy, because of all these petty quarrels in Gamma. The Elders have had to contain the situation in Gamma many times from civil war. Every complaint that reaches our ears makes our containment slightly less powerful. At this rate it is only a matter of time before it erupts through Gamma. This is undesirable, as I am sure you are aware. If you must hate each other, do not mix with each other. And always treat your brothers with respect, even if they do not return the favour.
