“Which, for those who may not know, placing a sell order for your shares (set an extremely high price), locks those shares so that they cannot be shorted by your broker”

Any shares held in a cash account can’t be loaned for shorting without the owner’s consent; and even with a margin account the owner can submit a directive prohibiting the broker from shorting any shares they’re holding without consent (usually only allowed by default).

Setting a sell order at a high price just lets the whole market know who believes urban legends.