IMO, it isn't clear that June 30 is a specific deadline. It...

IMO, it isn't clear that June 30 is a specific deadline. It could be slightly earlier or slightly later than that.
Here is the original announcement.
https://www.asx.com.au/asxpdf/20170703/pdf/43kcfnbhc7n586.pdf
The announcement is dated July 3rd, 2017.
But when was the MOU actually signed?
It might have been June 29 that the MOU was signed, or it might have been July 1 or 2 etc.
I cannot see where we have been told that the signing date was June 30, 2017.
There was a trading halt requests on Friday June 30, 2017.
All we know for sure is that the MOU has an initial term of 12 months, during which CAT have an option to buy a further $8 million worth of shares at 20 cents each.
But I don't think the date really matters.
The term of the MOU can be extended at anytime without it "going binding" whatever that actually means.

There are 3 things that can happen with the MOU.
1. The MOU can be be extended with the consent of both FBR and CAT. If this were to happen, then it is logical that this would happen well before the expiry of the current term and I would expect to see an announcement about it before June 30.
2. CAT could decide to exercise its options. Surely they would only do this if the share price was higher than 15 cents. Otherwise buy on the open market if they were interested in that.
If CAT did exercise their options then we would see an announcement.
3. CAT do nothing. MOU expires. I would also expect to see an announcement from FBR about what the new plan was.

In summary. I wouldn't consider that June 30 is any more significant than any other date in June.