Supercap maximum current rating
can withstand 150mA for 10-20 seconds when charging the capacitor from 0V


It cannot. Maximum voltage is 5,5 volts, and its ESR is 65 Ohms => max current is about 85 mA. 


  What is the meaning of the MAX current at 30 min. column ?


The datasheet has the answer: It is the residual current after 30 min. charging time (from completely discharged).