The acquisition share price is usually told to employees. They probably got the information from current employees. Since they are a shareholder, they'll eventually find out anyway.
I was involved in an acquisition as a shareholder. I was nigh impossible to get anything out of the executives. It was an acquihire so maybe things were different.
That...sounds illegal. You should at least have gotten a document in the mail with the buyout details, after everything was finalized and signed. It may take a few months in some cases but they have to send it out.
You're certain you were a shareholder and not an option holder? That is, you had exercised some of your options?
Another possibility, since you said it was an acquihire, is the company actually shut down operations and sold off its assets to the buyer. Maybe in that case there would be no share price to report since no shares were bought? I'm not an expert.
I was definitely a shareholder. I had early exercised some options, and reached my one year cliff. I believe your conclusion is correct. They shut down the company and sold off assets. The acquihire probably returned some money to the investors.
I spoke with (paid) two attorneys (employment and business) at the time and they said there wasn't much I could do. In the grand scheme of things it was small potatoes. I was pissed at the time though.