Tyranny of the majority is considered a pitfall of democracy, or consider how to enforce "the will of the majority while protecting the rights of the minority"
Until law mandates that all labor unionize - and as closed shops, at that - the rights of the minority are hardly impaired when any one shop does so. Open shops exist, as do shops with no union of any sort, and employees need not remain employees at all, of anyone, if they no longer so choose; they are free to start their own businesses, of whatever sort best suits them. Those who decline to join a union, even at a newly closed shop, are constrained only in that they no longer meet the requirements of the job at hand - and the "right to work", so called, does not extend so far as to establish, regarding any given company with a union or without one, a right to work there.
The plea to "tyranny of the majority" thus seems here to conceal a plea for the tyranny of the minority, in that they be allowed to frustrate their colleagues' strongly held and constructively expressed desire to obtain a more equitable balance of power in their workplace by recognizing their shared interest and forming a united bloc to match that which management and ownership present in support of their own shared interest.
One wonders on what basis this sort of tyranny merits more favorable consideration than any other.