Your assumptions are correct. If it was a free extra tile lay the rules would have said it was a free extra tile lay. The requirement that the track has to be connected is already specifically covered in section 1.2.4:
Section 1.2.4 Private Companies wrote:
A company must be able to trace a legal route to the location being affected by any private company which modifies track, adds tokens, or has some other effect on a specific location on the game board.