It is always convenient to take sentences or parts of sentences out of context in order to make a point, no matter how flawed that point may be. Unfortunately, the whole EASA Regulation (i.e. the Basic Regulation, the relevant Enabling Regulation, the relevant Annex and its AMCs and GM and, in some cases, other regulations) has to be understood if the context of an individual requirement is to be correctly interpreted. As we know, there is no cross-referencing and so this is not an easy task - even the CAA often finds difficulty in correctly interpreting the Regulations, as has been demonstrated by the repeated revision of CAP 804 and various Information Notices.
FOK avers, by implication, that Article 50 of the ANO refers only to student pilots (i.e. those who do not yet hold a licence) but this is incorrect. The Article refers to an 'appropriate' licence, i.e. one that includes the privileges appropriate to the task. FCL.045 makes clear that the privileges of an EASA licence may be exercised only if the relevant ratings contained in it are valid. If the rating has expired, the privileges of the licence may not be exercised, it ceases to be 'appropriate' and Article 50(2) applies.
To renew an expired class or type rating, the holder is required to undertake refresher training at an ATO. Paragraph 1h of Annex II to the Basic Regulation requires that all training must be executed through a training course. In the case of refresher training, the course is developed entirely at the discretion of the ATO and may well include both dual flight instruction and supervised solo flight time. There is nothing in any of the regulations to prevent this.