The lol is perfectly appropriate in the context it is used:

KATHRYN HESS CAN’T tell the difference between a coffee mug and a bagel. That’s the old joke anyway. Hess, a researcher at the Swiss Federal Institute of Technology, is one of the world’s leading thinkers in the field of algebraic topology—in super simplified terms, the mathematics of rubbery shapes. It uses algebra to attack the following question: If given two geometric objects, can you deform one to another without making any cuts? The answer, when it comes to bagels and coffee mugs, is yes, yes you can. (They only have one hole apiece, lol.)

I'm not sure what the people who are taken aback by it usually read -- or what did they expect to find here.