Good to know, but I would still prefer if they were NSOs and just didn't expire. The tax benefit is relatively minimal compared to the tax risk & cost.
The big difference here is the company is practically non-liquid and the employee is already taking a risk in working for that startup. I feel the 1 year vesting cliff alone is enough to evaluate if an employee is worthwhile and you should give the employee the full value of the vested stock compensation. Not add more gotchas to make the worth of the options even worse. If the company shares were liquid, then I wouldn't care as much.
Often over a few years you get the situation where the strike price is a good chunk over the FMV price and taxes are somewhat prohibitive compared to the probability that a liquidity event would happen. It makes the shares an actual net negative in total compensation and as a result, the open secret in the bay area is that most people don't actually exercise their stock options when they leave their companies. You get things like the ESO fund popping up in response taking a good cut of your compensation because you didn't want to pay some employees to do 20 hours of extra work a year.
Anyway overall, to an experienced employee who has stock option experience, it just makes your compensation package even less attractive and them less likely to work with you. If you show that you are willing to do this relatively minor & cheap thing, it will increase trust and make your company more attractive to work for, especially if your a non liquid company. I would really consider this as an early stage startup as a recruiting technique. This stuff is usually hidden in contracts, so I would bring up this feature of your company early on explaining the logic behind it.