No it doesn't.  First, it's not the place of atheism to argue for such a thing.  Atheism is not a philosophy.  It is only the state of non-belief in a deity.

Second, if any particular atheist has trouble arguing for meaning in life, it is because he has fallen victim to a fallacy.  He has created an equivocation by assuming the theist definition of meaning, which cannot be correct if there is no god.  In other words, OF COURSE an atheist can't argue for meaning in life if the definition of meaning involves the existence of god!  As it turns out, it's not difficult at all for an atheist to argue for meaning.  Where theists are unhappy is that there is no "higher meaning."  All there is involves this life, with no promise of anything afterwards.  This is not a lack of meaning, but a lack of mythology.

Only if you don't believe that natural selection has imbued humans with natural drives.

Anyone who arrives at nihilism from atheism is either naive or dense.

I don't know if you're naive or dense yet.  Why would you think that what happens in, say, the Andromeda galaxy has anything to do with whether or not you can find any meaning in life?  The person determining meaning is you, not the universe.  Do you get up in the morning?  Do you eat food?  Do you try to find love?  Do you love your family?  Do you have a hobby?  You have lots of meaning in your life.  What you don't have is the promise of anything after you die.  So what?  You have stuff you want to accomplish while alive, even if it's very mundane.

You could try, but you'd be demonstrating ignorance of natural selection, sociobiology, and evolutionary psychology.  The reason we have emotions like guilt are tied to something called the Commitment Model, which explains the mathematical advantage to a particular strategy of balancing self interest with reciprocal altruism while engaging in something akin to the classic Prisoner's Dilemma.  To put it very simply, we developed emotions precisely because we wouldn't be altruistic if we didn't have them.  Those of our ancestors who didn't have emotions were out-reproduced by those who did, since the advantages of community are so extreme for us.

You're completely ignoring the possibility that science can provide valuations.  You're thinking that nihilism results if we don't have an absolute standard, but that's another theist fallacy.  Our morality, like our natural drives, are subjective, but they are not arbitrary.   In the real universe, everything works within its own closed system.  To be human is to be bound by emotions pitted against rationality.  It is to desire sex, food, and power.  We have survival instincts.  We have feelings for our kin and friends.  All the philosophy in the world doesn't change that.  We can certainly choose to act as if we are not bound by our instincts, but only so far.  In other words, our course is subjective, but not arbitrary.