Depends on if you are a shareholder for the long terms (many years) or a short-term trader. I don't own stock in Boeing (or any of their main competitors), but when there is a strike like this in a company I hold stock in I generally get more bullish for the long term because it means that:

1. It signals employees still care about the company enough to not just quit and go elsewhere. And employees who care make a better product.

2. Negotiating better benefits generally helps retain the solid "middle class" who make the brunt of the work in a company. It might not entice the "rock-stars" or so, but they generally are not dis-incentivised by their colleagues getting better benefits either.

3. The C-suite gets to know they are not untouchable, this also helps keep them level when answering to the board of directors.