Munroe typically would have 90 students, and students usually don't have the option of opting out of a teacher's class, the principal said, "except when egregious or unique factors are in play."
He called the blog posts that prompted her suspension in February "crass and cruel."
Lucabaugh appeared at a news confernece with Superintendent N. Robert Laws and School Board President Paul Faulkner during which the officials offered their first public comments since Munroe's reinstatement was announced last week.
Munroe also has not commented since she learned she was getting her job back, but her lawyer said she preferred to work at another school.
Her husband said she will meet with her lawyer, Steven Rovner, before responding to the district's comments later this afternoon.
Munroe's blog drew national attention after Central Bucks East students found her posts and spread them on social networks. She referred to some students as "frightfully dim," "whiny," and "utterly loathsome."
In an October 2009 post, she wrote: "My students are out of control. They are rude, disengaged, lazy whiners."
She wrote under the name Natalie M. and did not identify her school, district, colleagues, or students. But the blog, called "Where Are We Going & Why Are We in This Handbasket," included her picture.
It regularly got "nine readers, two of whom were myself and my husband," she said in February, that it consisted mostly of innocuous musings about her daily life.
At an assembly after Munroe's suspension, Lucabaugh told students: "The sentiments are in no way representative of how we feel about our students or how the teachers and faculty feel about them. This is a representation from one individual."