Yes, of course, telling a deliberate lie is bad. But it doesn't change the fact that the list of the 6 types of Right Speech (MN 58) about telling the truth is fairly exhaustive (listing 6 options for when to speak) and omits discussing the potential beneficial aspects of skillful means as being either good or bad (in rare instances of course), not as a rule of thumb.
It doesn't say it is acceptable, nor does it say it's unacceptable.
By analogy, if I list all the letter arrangements of ABC as:
Someone would rightfully ask, "where is CBA?"
The sutta could have easily have just added (to make it more complete):
In the case of words that the Tathāgata knows to be unfactual, untrue, but beneficial, and endearing & agreeable to others, he does not say them.
However, the sutta does not state this final option above.