0.1 themink VALID Fantasy Rules must not contain greater than one word having any particular initial letter.

I judge this FR to be VALID.

It is consistent with itself, and is consistent with the RRs. The 'must not' caused a glimmer of doubt, as it seems to try to place restrictions on validity directly, rather than indirectly via consistency. However, I think it's perfectly reasonable to interpret this 'must not' as if it were 'do not'.