What will happen to the followers who received instructions from the one who fell down from his position

Hare Krsna,

HG Paramesvara Prabhuji has answered the below questions in this lecture:

http://paramesvaradasarns.blogspot.com/2017/07/q-on-july-23rd-2017-at-iskcon-chennai.html

Questions: 1) Material science itself is spiritual only, but the technology we can use for either material or spiritual. Material mathematics cannot be used for spiritual mathematics.
My Query : i did not understand fully the above statements,
especially, ' 'material mathematics cannot be used for spiritual mathematics'' ?

2) If one becomes a best follower and becomes the best leader , and later on, deviates , and becomes a bad follower , the initial acceptance of he being a representative of Krishna Becomes invalid. What will happen to the followers who received instructions/ advice/ time spent with such a leader ?

Please listen to the lecture to know the answers. Though the lecture is starting with Tamil, these 2 questions were answered in English.

Thank you.