234C Applicability on senior citizens

1. According to sec 207, advance tax needs to be paid by an assessee as per sec 208 to sec 219 whose income is chargeable to tax. 
2. However, the provision will not be applicable for resident individual 
i) who is above 60 years of age and 
ii) who do not have income from PGBP. 
2. Hence being a senior citizen alone is not the condition for not payment of advance tax but he should also not have income from PGBP. Then in such a case assessee need not pay advance tax. 
3. If an assessee falls under the above exception then he cannot be charged interest u/s 234B and sec 234C since advance tax provision u/s 207 itself is not applicable to him.  
Please correct me if the above interpretation has an alternative view. 

My friend became Senior Citizen during the year FY 2020-21.  Only for a part of the year he was in employment and retired.  TDS was deducted and remitted for I Qtr.   Thereafter, he has not remitted any Advance tax, as he is a Senior citizen having income from Salary, pension and interest.  However, one small payment was received as Professional fee during the FY for which TDS u/s 194JB was deducted.  Now, on assessment, interest u/s 234B & 234C are levied. 

a. whether he is liable under the provisions to pay interest as levied 

b. whether the small amount received as prof service charges can trigger for the demand of Interest u/s 234B & C 

c. If not, what is the next course available to him ? 

Pl clarify and advise.