Sure... but I'm not claiming that I can reach the same level of skill as someone who trains five days a week, and I'm certainly not claiming that I'm qualified to open my own dojo and award rank to other people.
Only training twice a week doesn't make you a bad person. There's nothing "wrong" with only training twice a week. It's just not enough to develop any real skill. (At any physical art, not just aikido.)
Edit: Actually, make that any art, physical or not. Writers, photographers, and people learning a language need more practice, too.