Yes, he can get the full amount by filing TDR, even without deduction of clerkage charge Rs. 30/-
Source of Info: Couple of weeks back when it rained heavily in South Gujarat (Valsad/Surat), I was to travel in Golden Temple Mail BCT-NAD. Due to late arrival of ASR-BCT twin, BCT-ASR train was announced to leave 2.5 hrs late from BCT. I has a confirmed tatkal ticket in SL. Around 5 hrs I wished not to travel, but was refused any refund at BCT as train wasn't starting 3 hrs late. Later, I decided to travel, but much to my amusement, it actually started 3.5 hrs late. I heard TTEs discussing - hehehe, we knew it will be more than 3 hrs late,...
more... but we smartly announced only 2.5 hrs delay, and actually flagged off 3.5 late, and saved lot of TDRs (not the IR's money, but the headache to prepare and give the same to passengers)