This is just another allegation out of context. Let us read what Ahmad(as) has himself written in the footnote:
“I observe a fast and I break the fast. This means that time plague will subside, and at other times, it will break out”-(Tazkira, Page 540).
Hazrat Mirza Ghulam Ahmad(as) clearly explains the revelation stating: It is obvious that God does not observe fast or break it. These words are not literally applicable to Him, they are used metaphorically and mean: I shall sometimes send down My chastisement and at other times I shall grant respite.… Divine books are full of such metaphors. For instance it is said in a hadith that on the Day of Judgment God will say: I was ill, I was hungry, I was naked etc. [Haqiqatul-Wahi, p. 104 footnote, Ruhani Khaza’in, vol. 22, p. 107, footnote]
The hadith is as follows:
” إِنَّ اللَّهَ عَزَّ وَجَلَّ يَقُولُ يَوْمَ الْقِيَامَةِ: يَا ابْنَ آدَمَ، مَرِضْتُ فَلَمْ تَعُدْنِي(1) قَالَ: يَا رَبِّ كَيْفَ أَعُودُكَ وَأَنْتَ رَبُّ الْعَالَمِينَ؟ قَالَ: أَمَا عَلِمْتَ أَنَّ عَبْدِي فُلَانًا مَرِضَ فَلَمْ تَعُدْهُ؟ أَمَا عَلِمْتَ أَنَّكَ لَوْ عُدْتَهُ لَوَجَدْتَنِي عِنْدَهُ. يَا ابْنَ آدَمَ: اسْتَطْعَمْتُكَ فَلَمْ تُطْعِمْنِي، قَالَ: يَا رَبِّ وَكَيْفَ أُطْعِمُكَ وَأَنْتَ رَبُّ الْعَالَمِينَ؟ قَالَ: أَمَا عَلِمْتَ أَنَّهُ اسْتَطْعَمَكَ عَبْدِي فُلَانٌ فَلَمْ تُطْعِمْهُ؟ أَمَا عَلِمْتَ أَنَّكَ لَوْ أَطْعَمْتَهُ لَوَجَدْتَ ذَلِكَ عِنْدِي. يَا ابْنَ آدَمَ: اسْتَسْقَيْتُكَ فَلَمْ تَسْقِنِي، قَالَ: يَا رَبِّ كَيْفَ أَسْقِيكَ وَأَنْتَ رَبُّ الْعَالَمِينَ؟ قَالَ اسْتَسْقَاكَ عَبْدِي فُلَانٌ فَلَمْ تَسْقِهِ، أَمَا إِنَّكَ لَوْ سَقَيْتَهُ لَوَجَدْتَ ذَلِكَ عِنْدِي”
Allah (mighty and sublime be He) will say on the Day of Resurrection: O son of Adam, I fell ill and you visited Me not. He will say: O Lord, and how should I visit You when You are the Lord of the worlds? He will say: Did you not know that My servant So-and-so had fallen ill and you visited him not? Did you not know that had you visited him you would have found Me with him? O son of Adam, I asked you for food and you fed Me not. He will say: O Lord, and how should I feed You when You are the Lord of the worlds? He will say: Did you not know that My servant So-and-so asked you for food and you fed him not? Did you not know that had you fed him you would surely have found that (the reward for doing so) with Me? O son of Adam, I asked you to give Me to drink and you gave Me not to drink. He will say: O Lord, how should I give You to drink when You are the Lord of the worlds? He will say: My servant So-and-so asked you to give him to drink and you gave him not to drink. Had you given him to drink you would have surely found that with Me.(Sahih Muslim #2569)
This accusation makes no sense against Hazrat Mirza Ghulam Ahmad(as) rather proves his truthfulness since Muhammad(saw) was revealed similar things. Now it is up to the reader to read it in context and if he had knowledge of Islam and Hadith, this accusation would not come up.