Unless he is full on retard, I'm sure Sabean at least inquired about Hamilton's interest/asking price, and is likely keeping abreast of the situation in the (unlikely) event he could be had for less than market. But knowing that would drag on for a bit and realizing in the end, he could be stuck holding his pecker and not getting Hamilton, Affeldt, Pagan or Scutaro, he did what he had to do.
I seem to remember similar voices saying similar things about letting Beltran walk, and going after Melky and Pagan instead. Hell, I was probably one of them!
Beltran ended up watching us celebrate as we headed off to win another title. Just saying doots, whether you love Sabean, can't stand him or you're somewhere in between (and all are valid perspectives), this isn't his first rodeo. I'd bet good money that he did his due diligence on JH, assessed the chances of him signing here, then went to work getting the band back together.