Pretty clear to me.
The fact that the speakers themselves have no coupling mechanism such as threaded holes to bolt the to stands means to me KEF prefers the LS50 to be "decoupled" from stands or whatever surface they're placed upon. Meanwhile the stands that KEF offers for them have spikes and room for inert damping fill, effectively solidifying their desire for the stand to act as a coupled, deadening place for the speakers to sit on.
KEF R500, R200C, R100, R50, SVS SB2000 sub, NAD T758v3 AVR, LG UP875 4K BlueRay, Samsung UN55JU6500F 4K LED TV, KEF M500 headphones, Sony CDP-CE500 CD changer. Office: NAD M10, KEF LS50, KEF Kube 10b, Pro-Ject RPM1 TT w/ Ortofon 2M Red. Guest room: Hafler 300 L-R, KEF Reference Model 100 center, KEF iQ10 surrounds, modded M&K V-90 sub, Bluesound Vault 2.