A bit off topic, but commenting on footnotes is fair play: I don't believe that 'let' is in fact autoantonymic. A let is more-or-less lost, as a noun in English, but in the form inlet and outlet it remains ubiquitous. In "let or hindrance" we might observe that a right of travel (a let) might well be a hindrance to other uses of the property. A let in tennis is so-called because you 'let' the server try again. The se…
https://duckduckgo.com/?q=let+tennis+hinder: the consensus among the first few results, which are reputable-looking sources, seems to be that the hinder sense is probably correct, though some suggest as an alternative the French filet meaning net.
https://duckduckgo.com/?q=etymology+of+let+and+hindrance: not much obviously canonical, but https://www.phrases.org.uk/meanings/without-let-or-hindrance... at least sounds reasonable, and agrees with me, including a citation in the last paragraph from 1799 which is unequivocally being used in the sense I nominated.