Order of Lewis acid character among sulfur hexafluoride, sulfur tetrafluoride and tetrachloromethane Problem

Compare the order of Lewis acid character of $\ce{SF6},$ $\ce{SF4}$ and $\ce{CCl4}.$

My attempt
Oxidation state of $\ce{S}$ in $\ce{SF6}$ is $+6,$ so it is very electrophilic.
$\ce{S}$ has a lone pair on it in $\ce{SF4},$ but can expand its octet if attacked by a donor.
$\ce{C}$ cannot accept lone pair from donor.
So, the order should be $\ce{SF6} &gt; \ce{SF4} &gt; \ce{CCl4},$ but that is a wrong answer.
S is in its highest oxidation state (+6) it has no electrophilicity hence not a Lewis acid.
Also, CCl4 can't have more than 8 electrons in its outermost orbit and it can not also increase it's coordination number also so it can't behave as a Lewis acid.
SF4 can accept electrons as S isn't in its highest oxidation state.
Hence order of Lewis acid character is : SF4 &gt; CCl4 = SF6