My guess is that they were a bit stressed out that they weren't really hitting jackpot at the time, especially as they are today. It was early 1999, they didn't really have that many good income sources at that moment(if I'm not mistaken, they didn't even have Adsense launched back then).
They went to these guys wanting to cash out and probably lay low for a year or two ... after which I'm sure they'd be back on their feet with something new.
Well Google truly is a garage story. Google the search engine existed before Google the company. If my memory servers me correctly there new found success caught them off guard, it happened faster than they expected. They had to incorporate and scramble for funds just to keep up with the volume that was increasing day by day. I would imagine that a sale would net them the infrastructure they desperately needed.
