No Any Srilankan Can be according to the Constitution ,thats y its called the DEMOCRATIC SOCIALIST REPUBLIC OF SRI LANKA , or else it cannot be democratic in the firlst place !!!
copied from the Constituion below !!!
CHAPTER VII - THE EXECUTIVE
The President of the Republic
The President of the Republic.
30. (1) There shall be a President of the Republic of Sri Lanka, who is the Head of the State, the Head of the Executive and of the Government, and the Commander-in-Chief of the Armed Forces.
(2) The President of the Republic shall be elected by the people, and shall hold office for a term of six years.
The election and the term of office of President.
31. (1) Any citizen who is qualified to be elected to the office of President may be nominated as a candidate for such office -
(a) by a recognized political party, or
(b
) if he is or has been an elected member of the legislature, by any other political party or by an elector whose name has been entered in any register of electors.
(2) No person who has been twice elected to the office of President by the People shall be qualified thereafter to be elected to such office by the People.
(3) The poll for the election of the President shall be taken not less than one month and not more than two months before the expiration of the term of office of the President in office.....(Cont..)
Source -
http://www.priu.gov.lk/Cons/1978Constitution/Chapter_07_Amd.html