I dont think thats how taxes work on the CGT method. The highest...

I dont think thats how taxes work on the CGT method.

The highest marginal tax rate is 45% (so 50% is already too high).
Secondly, you need to consider what the base cost of the total of their shares are. I've seen 4c floating around quite a bit. I am not sure if they were all offered at 4c or not.

For a hypothetical, lets say they did acquire all of their holdings at 4c x 3,750,000. (= $150,000 cost)
They then disposed them at $5.63
They have held this stock for over 1 year, so they get the 50% capital gains discount.

3,750,000 sold = $20,962,500
- cost = $20,812,500.

Divide by 50%
= 10,406,250

Times rough 45% marginal tax rate (I know that it scales up to $190,000, just doing this roughly)
= $4,682,812 tax liability.

Again, this is if all acquired are counted from 4 cents. (I am not sure whether they were or not).

~$4.5m on a $20m sale.

Correct me if I am wrong, but this is no where near the "25% of their net value in cash". It is closer to 75%.