More tellingly, I think; Pi isn't in love with her. Lord knows what his real reasons are for being there, but if he had really loved her and was living at Chez Castle for a month, he would have made an effort to get on Rick's good side, because if you love a girl, you are NOT going to antagonize the dad who is letting you essentially live with her. (Of course, it is possible that like the Pi clone I know IRL

, he didn't even realize that Rick didn't like him. Yes, I *do* know someone who is so much like Pi that it's scary.)
I agree that the joke will probably be that Kate is better with the baby than Rick is, and it is no doubt going to drive him nuts because he handled Alexis so well. Like most men, he probably didn't spend time babysitting for money, and as he is an only child who has an only child, his experience probably has all been with one baby. As babies, some kids are easy and some kids are not, and unless you have dealt with a whole lot of them, the tough ones can throw you some nasty mental curve balls.
As to Beckett and the toddler from S1, I know that a few minutes isn't several days, but in that particular case the level of physical confidence that Katic showed was noticeable even in that brief scene, at least I thought so. This is a woman who has spent a LOT of time with little children. (IME, You can always tell people who are experienced with handing young children by how they literally handle young children -- they have a noticeably casual and confident way of picking them up and holding them. You only get that level of muscle memory with lots of practice. Much as DH has always had kids gravitate to him, it wasn't until we had our own that he became confident at actually picking them up and casually holding them; as he never was physically responsible for little ones before that point. He was physically awkward with DS for at least a month. It will be interesting to see how well Fillion handles that physical aspect, because unlike Katic, he doesn't have younger siblings.)
PS: I should mention that I'm NOT the Pied Piper type; before I had my own kids I always avoided holding babies unless I was getting paid to do it, because little kids other than my own tend to hate me. All I have to do is say one word and they will start to bawl -- I don't even have to touch them to set it off. (I have a VERY low voice for a woman, and I'm told that my natural facial expression is a bit scowl-like.) Kids who know me well are fine with spending time with me, but kids I don't know are another story; I apparently scare the bejeezus out of them.
BTW, there's an extended promo up on YouTube for 6x07: http://www.youtube.com/watch?v=NUGZycXdz6Y
(Which, in turn, begs the question of how 19 yo Alexis "knows" a killer who committed his crime long enough ago that it's a cold case, and without her father knowing that she knew the guy.)