If the pattern is dependant on the type of yarn, than you should use what the pattern calls for. If it’s a plain, simple vest, than you probably could.
I’ve bought A TON of chenille yarn on cones on ebay. The price is great. However, I have found that I don’t knit with it. I use it for crochet, mainly. Knitting with chenille is tricky. It is virtually un-froggable. It also is prone to “worms” which are big loops that appear on the knit fabric for no good reason. Additionally, it has no elasticity whatsoever. Olefin in particular is very breaky and fuzzy. It would be hard to wear a garment made of it, as it would fuzz all over you. If you feel chenille yarn in Michael’s, for instance (like Lion Chenille or Caron Jewels) it feels very soft and strong, and does not shed. Olefin is not like that.
At the price you are probably going to pay, it’s not a big waste of money just to experiment with it, but be ready for a bit of a disappointment.