I’m not able to give you legal advice as I’m not a lawyer so I highly recommend you talk to someone in that industry of your options. But if you wish to re-distribute a OS project as your own then yes you must make it downloadable to the public that include your customisations and adhere to the original OS license/copyright agreements.
As I said it depends on what you want to do and you need to seek legal advice on that plan. Of course we love you want to use SuiteCRM but why the need to rebrand it? Its like… Why fork Wordpress and rebrand it and sell to a client as your own CMS? SuiteCRM has its own large community and supportive pool of developers, why add a layer of obscurity to the project?