As I mentioned here, there are 2 versions of Softaculous - free and premium. The free version doesn’t offer CP but neither does it offer WP. It’s basically just a trial version with only 55 apps available compared with 450 for the premium version. In fact, very similar to how Installatron operates.
As this is something that would in most cases be offered by your hosting company, who will undoubtedly be using a premium version, it shouldn’t be an issue. And if you did want to buy a copy of Softaculous for your own VPS, it costs a mere $12 a year.
If you find your hosting company uses Softaculous but ClassicPress isn’t available as an option, ask them to make it available. It will be there but they may not have enabled it.
If anyone does find that’s the case, then it’s very likely your hosting company hasn’t enabled it. I’d suggest asking them to enable it. It doesn’t cost them anything.
Also, for hosting providers supporting ClassicPress, you can add it to the Softaculous Top Scripts. This will help make it stand out more in the cPanel interface.