The only reason the image was posted was to be more transparent as a response to another user regarding the link posted.
There are mostly unwritten rules here but in the case of affiliate links with CDNs.. it would not be a competitor so it does not sound as if it would be in violation. However, without the further context that was posted later on.. it did look like advertising in a way.
Now, the CDN. Judging by the information on their website, unless it requires "SSL" on the origin server (not seeing any requirements for that), it should in theory work.
I'm not sure if anyone here would want to use a free trial on a CDN if they plan to stick with free hosting for a while or the whole time.
I should also add that X10's premium hosting is completely different to free hosting. Whatever happens under free (restrictions, issues, free [un]official support) would not reflect how it would be on premium. It works very differently almost as if it is a different hosting provider but with the option to migrate.