Good article!
No harm in erring on the side of a high value tone pot. You can still sweep the 0-250K range, and with it set in the higher resistance values >250K, it just means that less high frequencies are being bled off thru the cap to ground.
Unless you use a switch to bypass the pot, or one of those "no load" pots (takes itself out of the circuit when its full "open"), there will always be some signal (high frequencies) getting bled off. Whether or not its perceptible depends on the ears involved