Could our inclement weather policy be considered discriminatory?

Q: “We are a small organization with under 10 employees. Our handbook states that during inclement weather, we follow the rules for a delayed start based on what the school district is doing in our county. If schools are on a two-hour delay than we are also on a two-hour delay. Our boss wants to set a policy that for those who have kids in school this delay applies, but if you don’t have kids, or they are grown up, then the delay will not apply. I worry that this can be seen as some kind of discrimination based on the fact that staff whose kids happen to be grown up are generally “older” staff. Can we have such a policy? Also, can we tell hourly staff that they have to be to work on time in order to get paid, but salaried staff get the two-hour delay even though our policy already grants it?” –Anonymous, Nevada