No, it's not. (It just took a quick term search in their bylaws). They may fill the vacancy. They're not required to.
"Section 3.13 Vacancies. Except as otherwise provided in the Certificate of Incorporation of the Corporation, any vacancy in the Board of Directors arising from an increase in the number of directors or otherwise may be filled by the vote of a majority of the directors then in office, even if less than a quorum, or by sole remaining director, and the directors so chosen shall hold office until the next election of the class for which such directors were chosen and until their successors are duly elected and qualified or until earlier resignation or removal. If there are no directors in office, then an election of directors may be held in the manner provided by statute."
No, it's not. If the Board doesn't want to have an annual meeting, they don't need to.
"Section 2.2 Annual Meeting. Annual meetings of stockholders shall be held at such date and time as shall be designated from time to time by the Board of Directors and stated in the notice of the meeting. At each annual meeting, the stockholders shall elect directors to succeed those directors whose terms expire in that year and shall transact such other business as may properly be brought before the meeting. Written notice of the annual meeting stating the place, date and hour of the meeting shall be given to each stockholder entitled to vote at such meeting not less than ten (10) nor more than sixty (60) days before the date of the meeting."
Who's everyone? There's at least one that has no position in this and doesn't trust them, so there's that.
There's nothing stopping a shareholder from selling off and walking away. It's counterintuitive to hold stock in a company if a shareholder doesn't trust management and has no ongoing faith in future prospects for the company. It's not a complex analysis.
I think the more relevant questions are why stay a shareholder if a shareholder doesn't believe everything is on the up and up? And what is the basis for holding stock in a company if a shareholder does not believe the company is on the up and up? And even more relevant, to hold for so long when there is no trust that the company is on the up and up?