This article confirms and provides documentation on how the IPS policy is imported along with the SRX device's firewall policy.

SRX devices running Junos OS Release 18.2 and higher (that has a firewall policy with an IPS policy configured) can be imported into Junos Space Security Director. 

In the following documentation, you’ll see that the assigned IPS policy is imported along with the firewall policy.

Import a Firewall Policy that Has IPS Policy Configured