Praise be to Allah.
The fact that days are long in Ramadan is not regarded as a valid excuse that allows one not to fast.
This man made a mistake by not fasting during the days of Ramadan, even though he was not sick or travelling. No one has an excuse for not fasting because of the length of the day, so long as he will not face considerable hardship during the fast, in which case he may break the fast by eating or drinking as much as will alleviate the hardship, then he should refrain from eating and drinking for the rest of the day and make it up later on.
He also made a mistake by giving food to the poor, because giving food to the poor [instead of fasting] is only valid when one is unable to make up the fasts.
He also made a mistake by delaying making up the fasts all this time. What he must do is repent to Allah, may He be exalted, from that and from falling short in learning what is required of him.
The food that he gave to the poor when he was able to make up the fasts is not valid [to make up for not fasting], but he will be rewarded for giving it [as charity], if Allah wills.
If he is able to fast now, then he must make up the missed fasts and offer expiation for each day because of the delay in making them up.
The amount of expiation is to feed a poor person by giving him a meal, or one and a half kilograms of rice.
If he dies before fasting and offering expiation, then his heir may fast on his behalf or offer expiation on his behalf, paying the costs of that from his estate.
If he was not able to fast, then he must offer two expiations for each day, one for not fasting and the other for the delay in making up the missed fast.
If he dies before that, the two expiations for each day may be given from his estate.
Shaykh Ibn Baaz (may Allah have mercy on him) said:
If you delayed making up the missed fasts out of carelessness on your part, when there were times when you could have made up the missed fasts, then you must make up the missed fasts and feed one poor person for each day, as well as repenting to Allah, may He be glorified, for delaying that.
What is required for expiation is half a saa‘ of food for each day that you delayed making up with no excuse until the next Ramadan came. That is equivalent to approximately one and a half kilograms. The food is to be given to the poor and needy, and it is permissible to give it all to one poor person.
If you are unable to make up the missed fast because of old age or sickness from which there is no hope of recovery according to trustworthy specialist doctors, then the obligation to make up the missed fast is waived in your case, but you must still feed the poor, giving for each day half a saa‘ of the local staple food, whether it be dates, rice or anything else. May Allah help us and you to do that which He loves." (Fataawa Ibn Baaz 15/204).
And Allah knows best.