This does not address Peter's questions, but an employer's possible mindset. When I started in this business, my area had a heavy concentration in the tool and die industry. Most tool and die business owners sponsored profit sharing plans with a paired money purchase plan and made healthy annual contributions. The owners started getting annoyed with their 20-year employees, who were generally only in their early 40's, quitting and taking their retirement plan account balance, and starting a competing tool and die business. They knew the customers, they knew the pricing, and they would buy one machine with their distribution and try to take business from the employer where they had just quit.
The tool and die owners got together, and they all decided to amend their plans to only allow for all distributions at age 65.