SRS: Stock buybacks are when companies buy back their own stock from shareholders on the open market rather than investing in workers or equipment. When a share of stock is bought back, the company reduces the number of shares left in the market, which raises the price of remaining shares. Company executives have every incentive to buy back stocks, since most of their compensation derives from stock and a higher stock price makes them personally richer.

Consider the source. Communication workers of America appears to be a trade union (In effect, if not in name).
Their logic however fails in making the assumption that When a share of stock is bought back, the company reduces the number of shares left in the market, which raises the price of remaining shares.
The logical fallacy here is that the value of the company does not remain the same (to be allocated between all shareholders). The money used to buy-back the shares (on the open market) will only buy those shares if there is no market for them at a higher price. But the cost of those shares bought back reduces the company's assets by the value of those shares. This should not cause a re-evaluation of the remaining shares unless the company has spotted that the shares are undervalued, and is buying for this reason.

If anything company buy-backs show that the company has confidence in its own future, unlike when directors start selling their personal holdings when they can see the company is in difficulty.