When Leigh decided to point Opus Dei into the priory and received Silas as a dog killer to do the job, he left Jacques the Grand Master as the last target. We can imply that was on purpose, so that Jacques would know about the other 3 murders and move.

First, it'd be more effective to leave Jacques alive so he could act, which would be enough for Leigh to find the cryptex and the Grail. Maybe he could even persuade Jacques into becoming a new member of the next priory generation, which would render him all the knowledge he most wanted.

Second, as Jacques knew about the murders and started acting calling for Sophie, Leigh should be monitoring his actions and then find out Sophie was a relevant actor on the priory context. Still he remained at his house doing nothing.

Third, Jacques knowing about the murders and that he might be the next target, did nothing to protect himself. He was taken by surprise at the Louvre and had to take a painting out of the wall to activate security to try to save himself.

Even so, given these mistakes, there was nothing pointing Leigh or Opus Dei into Sophie, and no new information leakage. If Jacques had just pointed Silas into the wrong direction and did nothing else, none of them would know about her, and then the priory ppl presented at the end of the movie could just reach her later when things were settled.

By pointing Sophie to Robert so that Robert would help her find her true identity, Jacques not only knew his life was in danger and that she'd need somebody else to tell her the truth, but he also put her on on Leigh's and Opus Dei's sight, which put her in great unnecessary danger.