Actually, this is a little bit different.
1) if you sell the Company:
selling the whole Company or the whole shares you own is different.
- if you sell all your shares for an amount, then the amount is the key: 5M$ for your restricted shares means that you can have 4.5B shares or 2B shares, you will still receive 5M$
- but in your example, they are selling the whole Company so 5B shares. In that case, the conclusion is different. , Indeed, as per today, common shareholders would received 10% of the 5M$ (0.5M float vs 5B o/s). But in one year time, shareholders would receive 0.5float/4.4OS=11.36%.
2) is it free to retire shares
No. You forgot that 10% of the Company is own by common shareholders. So even if the ops react mechanically to a share retirement, their part of the pie will be smaller.
i.e.: they decrease the O/S by 50%: from 5B to 2.5B… so they retire 2.5B or their shares. Let's say pps is 1$ before and goes mechanically to 2$.
They owned 4.5B$ and after the retirement, they would own 4B$ (their remaining 2B shares multiplied by 2$.
Feel free to correct me but this is how I understand the situation.