If your security is poor then that will remain as is if it is strong then that also should not change as these mods just allow some hacks to phpBB to also work with PHP Nuke's versions. One MOD the Select Expand Contract MOD as used on
NukeCode PHP-Nuke Blocks Modules and Themes only allows Code Quote or PHP if you have that MOD to be selected or expanded or contracted with a click.
These MODs only add mostly cosmetic or in some cases functional changes to already working aspects of the phpBB forums as used with PHP Nuke's implementation of the phpBB forum port. As with any software you should consider the security that any modification might do for your site and test it for such issues.
As with all software or modifications to such such a concern should be taken into consideration. In the cases if most of the MODS I deal with installation and PHP Nuke versions are more of an issue than security.
Thank you for the question!