To go back one step, saying a manager must decide alone otherwise it's an escape from responsibility is quite a bizarre claim to make. Making a decision without consulting your team, when your goal is to establish trust, will 100% backfire. It will come back to haunt you EVEN if people agreed with the decision, simply because that decision was taken arbitrarily. That such important decisions could be arbitrary, without meaningful involvement of the team, signals to the team that they are all at the mercy of such future arbitrary decisions. Finally, consulting the team does not mean that the decision is carried by everyone. A consensus should be sought, and the founder would be foolish to make such a decision against his team, but ultimately, the founder is in charge of the final decision and will bear the responsibility for it.
In my opinion I’d make it clear that the termination and the equity decisions are separate, that it was a bad fit but that you are building a culture of doing right by people. That doesn’t mean eliminating vesting, it means that you approach these exceptions on a case by case basis. I’d say 6 months vest would be fair, given the performance management issues - and it strikes the right balance showing you won’t be pushed around and that low performers will not be treated the same way as high performers.
If: a) other employees did not think the fired person performed poorly b) the decision of firing without compensation just before the vesting period is made by the founder only
then this will be a nightmare for the founder.
If however the contrary is true, ie that most people think the performance of the person being fired was poor, and if the founder discusses compensation options with others who will also be vesting at some point, then it signals that the founder actually cares about and trusts their employees enough to associate them meaningfully to the decision process. It also shows not just a wish but an active effort to ensure fairness for all, both the person being fired, and the others staying on who would be that bit more diluted in the cap table if somebody who shouldn't have vested is allowed to.
Good on you, dear founder, to be seeking advice and to be trying to do the right thing. You don't have to be alone thinking about that decision or making it, and you don't have to be alone living with it afterwards. Allowing your employees to be stakeholders in this is really key.