We have rolled out an update warning people about chapter gaps, no matter how you enter the chapter. This should be sufficient warning to prevent people from getting accidentally spoiled.
For the record, if the uploader is uploading future chapters for the sole intention of pissing people off, then that it is a dick move. However, it is near impossible to have a rule which covers these situations, because "uploading in bad faith" can't be proved, and "uploading future chapters" also covers legitimate cases where it is necessary to do so (official chapters, groups who have pulled out, etc)
Therefore we believe that this new function that warns about gaps should be sufficient. If the reader goes on to read it knowing that there's a massive gap, then that's their fault. It should be impossible to get spoiled accidentally now.