I can look at this from 2 additional perspectives:

- OpenTTD (a game I truly love and have followed since before the 0.3 days) was not born as a clean-room reimplementation of TTD. It started as a disassembly effort, something which is perhaps morally gray, especially if you take into account the original TTD was coded in assembly (with sprinkles of C). Perhaps this way there is some vague contribution that goes towards Chris Sawyer?

- This is a way you can legally get the original graphics of the game (GRF). Although I think the shareware version technically also worked...