I don't see how this could be looked at as odd.
WDW decided to change the standard for DAS. It was NOT because DAS was being underutilized or wasted. Either because of fraud, abuse, or just overtaxing of the system, it was felt that the impact of people using DAS and LL was too high and changes needed to be made.
So in a situation like this where you have 5 people, only 1 of which requires an accommodation, I would think it should be expected that the new program is going to limit the use of DAS for people who don't need it. Here to the child who needs it, and one custodial parent. The other parent is more than capable of monitoring/handling the 2 other minor children who do not need the DAS accommodation.
Would it be nice to keep everyone together, sure. But the DAS isn't about being nice, or making accommodations for people who don't need them. For the system to really work well, it should provide an accommodation to those who need it, while having minimal impact on operations. Adding more and more people to the system who do not really need the accommodation is what caused the breakdown that they are trying now to remedy.