er no, bookend, the compiler is NOT saying there is only one correct answer - you have surmised that as there was only one answer given as the solution.
This is what the Telegraph Crossword people had to say:
Where there is an alternative spelling, the compilers try extremely hard to make sure that the ambiguity is removed by a solution that crosses it. Where there is genuine ambiguity then, yes, alternative spellings would be acceptable, but we aim for this not to happen.
Kate Fassett (Telegraph Crossword Editor)
The Weekend team strive to avoid ambiguity at all times. However, this
is sometimes unavoidable. Rest assured that where a known alternative is
used in a solution that has been sent in it will be accepted.
Unfortunately, there is no way of representing this in the solution grid
that is published the following week.
(Kate Mepham and her editor Jon Stock)
I agree that, as far as the Herculis crossword is concerned, there is space for alternative answers when the solution is published but if one does not accept what has been stated, is there really any point in doing the crossword at all?