This is absurd. A "right to a fair trial" is the standard for criminal trials, which are associated with criminal punishments -particularly but not always- imprisonment and execution. The right to a fair trial has never been a standard we as individuals are obliged to follow in other contexts; for example: it would be ridiculous to think "a trial" is needed before we decide whether we should continue doing business with a company that dismisses its employees for being gay or trans.

Similarly, there is a long history of consumer boycott movements to pressure both companies and nations into acting more ethically; from Apartheid South Africa, to confectionary and fruit companies, to oil companies, to which eggs we might choose to buy. In none of those circumstances is a "right to a fair trial" a relevant concern.

A better question might be: How unethical does a company have to be before the act of just working for them should be considered immoral enough to merit public rebuke and repudiation? I don't think there's a lot of companies that reach that threshold, but I'm adamant that some should: Blackwater is the most obvious choice here.