With conservatives coming onboard with twitter, leftist speech will be countered in logical/realistic terms thus educating those who have been accepting leftist speech with no criticism of it.
Leftist speech should not be banned but there will be the opportunity to expose its faults, much like Free Republic where various articles are published and the users dissect it.
My problem with conservatives these days is they only see two possible outcomes:
—Leftists win
—Level playing field
A third option should be on the table.