Surprised they can do that. When a company I had shares in merged (UK stock exchange, and many years ago) they had to write to us and ask if we wanted cash or shares in the merged company. Of course the cash price/share swap was balanced in such a way that only a fool would go for the shares, but they had to offer.
Here in the US they don't need to do that. Its common that merges are paid to share holders via either stock in the acquiring company or flat out cash. The shareholders are able to vote on the merger (but us small investors don't count much, the mutual funds and large investors hold a majority of the stock) and the cash price is usually a premium over the rater on the date that the merger/acquisition is announced.
For example Amazon.com acquired Whole Foods a higher end chain of grocery stores with organic and conventional foods, they paid flat out cash for the shares of Whole Foods.