Is it permissible to adopt the view of the Hanafis and Shafi'is that pubic hair is not an absolute sign of puberty, and the view of Ibn Taymiyyah that there is no obligation to make up fasts for one who abandoned them out of ignorance of their obligation?

It is permissible to follow the opinion of those who say that puberty is not confirmed by the growth of pubic hair. It is also permissible to follow the opinion of Ibn Taymiyyah that one who misses fasting due to ignorance is not obliged to make it up. An ordinary Muslim is permitted to follow any of the recognized madhhabs (schools of thought), provided they are not merely seeking out dispensations.