What is your research based on? The section of the Act has been pointed out for you and yet you disagree with it with no evidence other than your opinion. If you read the section 650B which has been referred to you will note that the purpose of the section is to explain how a bidder MAY VARY an off market take over bid. And then, just to be clear that the offer can be varied during the offer period, it notes:
"If the bidder increases the consideration during the last 7 days of the offer period,
subsection 624(2) extends the offer period by a further 14 days."
This clearly stipulates that the offer can be increased during the offer period, even including in the last 7 days. If you read 624(2) it makes similar remarks, which is that offers can be varied to improve consideration and if done so within the last 7 days of the offer period, the offer period is deemed extended for 14 days (presumably to allow time for the fence sitters to make a decision about the INCREASED CONSIDERATION which a bidder MAY VARY).
If you sell on market, that should be based on your own research and risk assessment as usual. The offer is just part of the market 'game', until accepted.
Put simply, if OZL do not get the % they want, they may increase the offer in the absence of any 'higher bid' in order to get the crown jewels.