Meditation is directed towards getting rid of the discursive behavior of the mind and then the mind itself
Since any attempt to control the mind is an immense challenge to begin with , it is easy to understand alcohol is a no no.
The harder thing to understand is the role of non vegetarian food and meditation. The effects of non veg to the mind is not immediate but takes years to manifest. Hence it is likely to be not understood. Vivekananda gave a comparison between an elephant ( standing majestically) who is vegetarian and a restless prowling lion that only lives on meat.
The truth is far more difficult to grasp and even more difficult to experience. From fear of transgressing spiritual laws I cannot state certain things, but certain diets are known to bring stuporous states – which a hasty ignorant person can equate to the nothingness of Brahma. Of course this stuporous state is far from the fullness of Brahma
Some may argue that this diet restrictions is related to living and non living. However, we know that there is life in plants too
The final most difficult thing to understand is the question of eggs. Eggs can be Unfertilized. Yet they are prohibited for meditation
The guru who is capable of giving you the highest would like to see the seeds of the highest grow in the disciple. This seed of sohum WILL NOT grow if the disciple will not adhere to the diet for decades.
The disciple may lie but the discerning divine guru automatically knows the right thing. The divine Goddess will refuse to grow or let the Guru give awakening in these situations
Some people argue that Jesus ate meat etc on occasion. Jesus forgave the people who crucified him even though he was in excruciating pain. Can you do that ?