The defendant spoke vaguely and was unwilling to discuss the important matters.
Literal
Defendant [topic-は], vague things [object-を] talked [then-て], important things [object-を] talk [wanted-not-たがらなかった].
曖昧なこと means 'vague things.' かんじんなこと (肝心なこと) means 'the important thing.' ~たがらなかった uses ~たがる ('to show signs of wanting to') in the negative past — the defendant showed no willingness to discuss important matters.