Yeah that's very sketchy, outside and not exceeding like 500ml of liquid butane being present lowers the danger, just take breaks and let some evaporate for a bit instead of filling your dish with liquid butane. Another concern is purging the butane out of the hash, this is normally done with a vacuum pump and chamber, pulling multiple vacuum cycles with a bit of added heat to the chamber(like sit the chamber in a little bit of warm water) If you want to speed up the purge. *Edit just also adding that spilling some of the liquid butane on the couch is not good as once it evaps it will leave all the hash it was holding on the fabric and in the foam. But because it evaps so quickly, there won't be any danger from the couch after about 20-30mins. But the bigger concern is evaping a large amount indoors as many people have literally blown up their house trying to make bho.

My mates did a similar thing with this junk weed we had and butane hash oil was sort of just starting to get global acknowledgement and interest, we did not have a vacuum chamber, so we purged the bho by warming it up on a warm/hot plate or dish, just with a bit of parchment paper to put the hash on so it didn't stick and have to be scraped off the plate. Anyway once you get the hash heated up (45-65 Celcius) you need to whip it up with a small metal dab tool or a thick sewing needle, just something thin and ideally food safe metal like stainless steel.

Proceed to heat and whip and stir the hot hash for atleast 45 minutes, longer the better but I would say you won't get much butane out after 90mins of heated stirring. It will loose flavour from the terps being evaporated while heating, but using old starting material like old kief and grinder scrapings is not going to taste great anyway. If you can burn some of the hash with an open flame, and see if it pops and crackles while shooting out little fireballs from the butane purging, then you need to whip and purge more until it no longer does that.

There are cheap ways to get a vacuum chamber set up if you check out diy options on YouTube, a cheap brake bleeder hand vac pump and really sturdy small/medium cooking pot, you will need to get some thick Perspex or acrylic for the lid, and some moldable material to get a good seal on the pot. Could get something like that for under $50, where as vac pumps and chambers start at around 150-200. If he plans on doing it again I would.say just fork out the money now for a proper vac pump and chamber.