Yes, companies should be allowed to suggest who their employees should vote for, as long as they are not penalized in any way for not voting for the preferred person. Companies should have freedom of speech just like any other person or organization should be allowed to endorse a candidate. But it should not be forced.
Companies should be allowed to make suggestions to their employees about which way those employees should vote. People working for companies are doing so because both the employer and the employee find the arrangement mutually beneficial. If the employee does not want their employer to make suggestions about how they should vote, the employee is free to look for another job. Companies should be able to mandate many things of their employees.
Companies often have interest in legislation that will increase or decrease their bottom line. It is not their responsibility to inform their employees on public policies or government legislation. Information regarding current events, current legislation and current candidates is the responsibility of the individual person and can be found on their own without undue pressure from their employer.
Yes, the question specified companies, but I feel the need to specify that I find no issue with individuals within companies suggesting voting choices to one another. This would be nothing more than political discussion between people with the same employer.
The threat lies in a corporation/employer using its inherent power and intimidation over employees to influence their votes. However, said influence would mean very little if workers are informed that any reprisal from their employers for this reason would be discriminatory and illegal.
Companies should not be allowed to suggest to their employees who they should vote for. To do so would violate a person's rights to their freedom as citizens. Nothing is more freeing than the ability to vote for President, but if a corporation starts telling us who to vote for, then the actual feeling of being a free American seems taken away.
Companies should stay completely out of politics. You do not want massive corporations swaying a democratic vote at all. As a matter of fact, I wish there was an amendment to the constitution separating business from state the same way that church has to be separated. It's very dangerous and can cause long lasting harm.