Maybe the asker just wondered the difference between "too" and "so"? Why discuss about whether drinking at an old age is possible or not, instead of saying if it is grammatically right or wrong? (Not logically, grammatically. Because the asker can think if it's ok to drink at an old age or not in her/his own language.)
I answered the difference between "too" and "so" in this context in my very first response - post #2. We have then gone on, as we frequently do, to discuss the contents of the OP's question and link. These discussions can be very informative and useful and, of course, they give learners a chance to see a discussion between native speakers using the language we use on a day-to-day basis. We always endeavour to answer the question first and then, sometimes, we continue the discussion.
The asker can ask what they like in their own language. He/she chose to ask a language question here. In addition the discussion over whether or not "too old to drink" makes sense is helpful from a language basis. We have said that "He is too old to drink" is
grammatically correct. However, the OP should know that if they make such a statement in an English-speaking country, they may well be met with the same kind of reaction they got here, ie "What do you mean "too old to drink"? What a ridiculous notion."