The only thing I'd trust Farage and UKIP to plan is a trip to the pub. They seem good at that.
May is acting out of self-preservation, and (secondarily) preservation of her party. The good of the country comes a distant third, if at all.
According to all indicators a no deal brexit is absolutely unacceptable to most members of parliament. May advocating for such would mean gaining the loyalty of the ERG, but would lose the support of practically everyone else in the conservative party. On the flip side, ruling it out would mean losing the support of the ERG forever. Either option would fatally compromise her already tenuous grasp of power. That's why it's going to be a free vote this evening.
"hard brexit is the default legal position, the only option we can unilaterally implement and the guaranteed version of brexit"
Very true. Just as cutting your own bollocks off is the only way to unilaterally guarantee that you'll never have to father children.