Not too fast here
Phylosilicates are more than just clays. They are generic sheet silicates, and include metamoprhic minerals like Mica.
Note that we have already seen evidence of Carbonate and phylosilicate minerals on Comets. They may be formed in the transient hot and humid conditions at the moment of meteor impact into an icy body with some silicate minerals, or into a silicate body with some icy zones...
They do NOT attest to liquid water.