There is SETI (Search for Extraterrestrial Intelligence), for example, that specifically tries to detect intelligent life elsewhere in the Universe. So regarding lifeforms, it could clearly be argued it at least affects our methodology in trying to detect them. If intelligent, then as SETI assumes, at some point in time they will develop radio wavelength communication capability that we can detect by using radio telescopes and listening to the Universe. If however we'd be just trying to establish if some distant planet currently (in astronomical sense, so apply the time needed for the light to travel the distance) hosts air breathing and carbon dioxide or oxygen producing Earth-like carbon based lifeforms, we might want to detect that through radio-astronomical spectrometry.
So I say yes, this site should allow questions related to extraterrestrial life and their possible lifeforms, but not in a speculative way asking directly about them and what we couldn't possibly answer, but if the observations that are inquired about specifically target one or a few aspects of these lifeforms or their stage of development, then I don't see any objections. I suspect we might get many questions regarding the search for Earth-like planets, so with that in mind, those questions would already be implying possible support for a specific type of life form at specific stage of technological and scientific development - us. Tho we're not extraterrestrial, we do have common criteria that specifies our range of function. Describing an extraterrestrial life form with the purpose of asking about our possibility to detect it should thus be equally acceptable.