Hmm. One thing to keep in mind is that part of 4E design is that they don't want to have classes or paths with too specific a focus - since that often will mean they are too powerful against their intended foes, while being useless everywhere else. Instead, they tend to opt for something that can be effective in any situation, but gains some specific advantages against their intended enemies.
Which is what they did here... but in a rather subtle (but interesting!) way. The thing to note is that the class has a lot of focus on giving allies saving throws and bonuses on saving throws. These are useful in all sorts of scenarios, but It is not unreasonable to say that they are almost invalable against some of the most famous aberrations: Aboleths, Beholders, Mind Flayers...
A quick search through the MM shows only a handful of aberrant creatures that don't inflict ongoing effects - they clearly don't always have them, but it does seem pretty common.
Thus, the Guardian of the Living Gate ends up quite useful against them, but still can make use of all his abilities against plenty of other foes.
It is still quite a strange path as a whole, seeming to be a mix of Leader and Controller (and even a bit of Striker). That lack of focus might be one reason the path reads so strangely, though I imagine it is perfectly effective in play.
