These sort of articles need to be taken with a pich of salt. they are written to cause debate and disagreements..

The article clearly mentions that the last grand mufti "Sheikh Bin Baz" was against the celebrations. It then states "Saudi Arabia's most senior Muslim cleric recently denounced birthday parties as an unwanted foreign influence, but another prominent cleric declared they were OK."..

Ofcourse it doesn't give the name of the "other prominent cleric"..

I think its best not to take these types of stories too seriously ..