3 weeks would be too long for me too, and i dumped someone for this reason.
But thats his choice if he is busy, and really, who am i to say he has to state up front what time he has etc... I met him, we had a few dates, he wasnt all that free and it was one of the deciding factors to end it.
I certainly wouldnt suggest that all men on dating sites needed to make sure they had lots of free time before they even thought of dating.
Bant met someone he liked, shes not free, end of. Its just one of those things. He can either wait or not, thats his choice, but she shouldnt get chastised for her situation or told she ( or indeed , any other dating woman) is wrong.
People date for all kinds of reasons, to some, one date a month, a chance to go out, hopefully have fun and a nice evening, and thats it, thats all they want from it. Some want something to lead to more dates,and some are looking for something long term. Its all fine and its all allowed.
I only have every other weekend free. That said, if i REALLY want to, i can get babysitters. There are ways round things if you want there to be, and if you dont, then its a handy excuse :)