I don't know why some are expecting an explanation for these genetic messes... We didn't get one for the magically spawning facehuggers in the 2010 effort. They just appeared when required.
Whether this Alien type fits with what was represented in the films, I'd say no. It's simply not necessary. If they wanted that gameplay mechanic, just have the normal ones spray acide in a pressurised effect and spray you like they did to Drake if you get too close. Gives you an added incentive to stay away and, thus, generates authentic cinematic fear while playing through, too.
If they wanted new types, there are ways to have introduced animals to the equation, even if it's somehow working in livestock from a transport ship which was somehow passing by and got caught in the events (there are multiple different ways of doing that). All of this stuff just smacks of ripping off 'Left 4 Dead' and, as an unfortunate result, disempowering the 'normal' Aliens to pure cannon fodder.
Remember Ripley and Hicks and how they kept emphasising to the view how letting even one get past defences would result in total catastrophe? Mechanics like this obliterate the power of that sentiment, when a game should be backing it up.
Would also assist the developers, too, since they could use all the time spent on designing and refining new versions, on making just the two main types (adults and Queen) as incredible as 2012 allows.