conscious and conscience

The Anglican Archbishop of Sydney, Dr Glenn Davies, was reported as saying that he had ethical objections to the Oxford vaccine because it used cell lines from an electively aborted foetus.  Dr Davies was reported as saying: I probably would [wait for an alternative vaccine] but that would be a personal decision of mine and not a decision that I would bind anyone’s conscious with’.

 I always pause to consider if an error is possibly a typo, but the distance between conscious and conscience is I think too great for that to have happened.  So was this written by someone with no religious background, someone who has never been taught that your conscience is that little voice in your head that tells you if what you are doing is right or wrong?  On the other hand, the writer is perfectly familiar with pop psychology and the conscious mind.  So hearing conscience the writer prefers to leap to the familiar word conscious which aurally is not so far away.

 Just for fun I checked Google Ngram on conscience and found that peak frequency was in the early 1800s but by the 1900s the frequency had declined dramatically. It was used five times as often in the early 1800s as it was throughout the 1900s. It has picked up a little since 2000 but is still not a word that is used much.  I wonder why.