I think the outburst is just the combination of these things together.
For one, Woojoo was already angry that Hanbyul's picture was being used for the scam (maybe she still is very conscious about the non-consensual photo incident, as well, even though it was all cleared up by being Seulgi's -Hanbyul's sister- fault?). Add to that that she easily put one and one together about their fight from before (however, with some details wrong, lmao?) or simply jumping to that conclusion, lol (admitting, once again, that Hanbyul has a pretty face, lol).
I mean, she knows Hanbyul could be a bit naive... but, at the end of the day... maybe she knows him a little bit better than what she knew (or assumed) about Chulho. She still worries about Hanbyul, pretty face or not, despite their attempts to distance from each other.