A holder can only reverse their decision if a right to withdraw...

A holder can only reverse their decision if a right to withdraw arises under the corporations act (read point 17 on the Bidders statement (ASX announcement 15/3 4.33pm).

In my opinion, you can pretty much bet that Taurus won't be letting that happen.

Holders should also note a paragraph in today's letter to shareholders. It says about sending your signed form back now may mean you do not qualify to get the full price if a takeover offer is made by another entity (other than Taurus).

As shareholder correspondence has stated, sending your form back now will not achieve a quicker pay out.
There is no good reason, that I can see, for anyone to sign and send back your form at present (unless you are happy to receive 90c/share), until more information is forthcoming from the independent directors.