She wasn't 'trying' to say anything - she called him illegitimate - which, according to you, apparently means Baba's father didn't marry his mother because the latter was characterless. While what it actually means is what I said above - a child born out of wedlock. I retierate - your assumption is insulting Baba's mother - not the statement. Definitions do not change as per convenience.
No one is changing any definition. An illegitimate child is one who's born out of wedlock. And it is one undeniable truth that in our society, mothers who give birth to children out of wedlock are not considered respectable and noble.
Now if you wanna say that Lopa meant to say that Baba's mother was actually very respectable but only because of some unfortunate unforeseen circumstances their marriage could not happened then I've nothing to say. Keep maki your imaginary explanatory fiction stories.