It is safe. The rules block direct access to a .php script inside the /wp-content/ folder. I assume you had/have a security plugin that installed the file (NinjaFirewall doesn’t create .htaccess file).
You can keep it.
Yes, i have installed Sucuri but since it is a free version as well it does not include firewall. Beside, recently Sucuri firewall blacklisted my IP without absolutely any reason known since everything is clean and updated on my site for ages as far as I know. I’ve tried to contact their support but they have worst support for free users I have ever seen for my whole life. I got no reply from them and there are free users that have not been replied for over 6 months, such a shame. That is why I have installed NinjaFW at first place and I am very happy with it so far. Not to mention speed of support I got here as a free user. Really professional and I appreciate it a lot. Gonna recommend NinjaFW to my friends for sure.
Since I am having some critical warning in NinjaFW here and there I added/installed NinjaS to stay sure my site is clean. Btw, site is on Cloudflare which also has firewall so I hope all these layers of security plus WP installation hardenings should keep me safe.
Many thanks for such quick reply and clearing my case.