I think it's not meant to be taken literally anyway. How can someone become an aalim without knowing Arabic or tajweed or usul Al fiqh etc. The tag line is probably just to show how important the book is. The part where he said that people may challenge ulema due to something they've read in bahar e sharia- isn't that a good thing? They're challenging you on the basis of reading something in a legitimate book, not based on the information they received from some random rickshaw driver. If the aalim can't stand up to scrutiny and questioning, maybe he can go and find out the answer and increase his own knowledge as a result.