You know that the 2.4GHz wifi signal can have an advantage over the 5GHz signal?

2.4ghz also gets through walls better.

They just don't think outside the box. Even if 2.4 Ghz radiates better through walls, you don't need a contact if it's crawling under the bed. A good 5 Ghz Wifi would be enough, but they don't think that far ahead and don't want to operate a 2.4 Ghz network just for their cleaning devil.