Unless Borgeson told you to use antisieze on the threads their torque recommendation is moot.

The use of and type of lubricant used can have a profound effect on torque readings.

If Borgeson did specify antisieze that can account for the difference between their recommendation and what the FSM calls for.

A look at a generic torque specification chart may shed some light on this.

Here's what Antisieze has to say about it

https://www.antiseize.com/PDFs/torque_specifications.pdf