I disagree. First, if Salma stayed, she would steal the show from America's role as Betty. I don't care to see that.
Secondly, Sofia's character doesn't seem as admirable to me. Yeah, she was kind to Betty in the last couple of episodes, but she's giving her the "easy" way out by offering her a job. And how does she know Betty is wasting her time at Mode? Betty would learn a lot more about the real world by going through hard knocks at Mode than working at MYW. Also, IMO, I think Sofia's isn't telling the entire truth to Daniel. She seems to be hiding something from him. And if I'm right, that would be a slap in Betty's face, since SHE went through all that trouble of getting Sofia and Daniel together. In that sense, Sofia would be the jerk for playing everybody - from Daniel to Betty.
Yup, I don't care to see her stick around. Seemingly perfect Mary-Sues like her don't cut it for me.