If they had waited longer, their share price would likely have drifted down as the perception that the raising would be coming soon would be heightened further. So they may as well do it when there was a bit of a spike in the share price.
I have held PRU since the 20's several years back and I have lost count on how many times shareholders have complained about the many capital raisings since then. They are now $3 + so I aint complaining! As long as the money is going into building up the resource base / getting us into production etc the gains in future share price will well and truly offset the short term pain of dilution.
SBL Price at posting:
2.6¢ Sentiment: Buy Disclosure: Held