Provision related to section 23

Yes, mandatory for interstate supply of taxable goods....

compulsory registration under section 24 for inter state supply of goods irrespective of turnover.

Yes, as he has some inter state supply of goods, so compulsory registration is required as section 24 of the CGST Act, 2017.

But in ICAI study material it is mentioned that registration is not compulsory.....

Dear Anuj
Either you have mistyped something in your query or you have not interpreted the study material correctly.

Actually , as per Notification 56/2018 , person making inter-state taxable supplies of specified handicraft goods is exempted to obtain mandatory registration u/s 24 ,(Note his aggregate turnover must be below threshold as prescribed in Section 22)
So if he supplying any taxable goods(Not handicraft goods) with specified taxable handicraft goods interstate then he is liable to take mandatory registration under Section 24 , even though AG turnover is below threshold limit .

(Section 24 is over rides the Section 22)

Yes if he is supplying taxable services interstate along with handicraft goods then he is exempted to obtain mandatory registration u/s 24 , because Interstate supply of SERVICES is exempted by Notification 10/2017 CT.