Learning forefoot running on a treadmill is a bad idea for many reasons.
According to a recent study, running on a treadmill barefoot, not in shoes will help you maintain your forefoot strike.
Learning barefoot/forefoot running on a treadmill may mute proper gait adjustments to attenuate shock.
When compared forefoot running outside (overground running), forefoot running on a treadmill may increase contact-time and relative loads under the arch and metatarsals.
I always feel a little unstable running on the treadmill as compared with running outside, because of this, I much prefer to run outside.