ahhh so much misinformation in so few posts!!
first thing id like to address is propane extracts...
they work exactly the same as butane extracts, they are both non polar extractions.
second what he might be referring to is either a sub critical extraction or a super critical extraction.
either of those are going to require about 5 thousand dollars worth of high pressure vessels and a pricey machine to regulate everything. i doubt anyone does either of these to be honest, more of a marketing ploy than anything else. the product you get from co2 extracts are not that good.
the beauty behind bho is that your extracting cbd with thc as well as other terpenoids, super critical extractions only extracts a single molecule form at one time,.. hence the less than desirable product with marginal yields.
if i were to bet id say hes selling you bho and trying to pass it off as his "secret method"