I haven't really heard it explained like this ...''opportunistic.''
from the OP.....
My contention based on mainstream science is that Abiogenesis is the only scientific answer to how life first started in the universe.
It certainly to the best of our knowledge was not created from or at the BB. The BB was the evolution of space and time [as we know them] at a time of t+10-43 seconds. From there and though a process that was a result of decreasing temperatures and pressures, and expansion, our first atomic nuclei was created at around 3 minutes. 380,000 years later, temps and pressures were such that the first light elements of hydrogen and helium were constructed. Still no life!!!
From there, stars, galaxies etc started to form...time frame around 400 million years post BB...still no life. From there the story gets more familiar and far more validated with eventually the formation of life from non life....or Abiogenesis. Again there is no other scientific answer.
In other words, at one time there was no life, then there was.
While we certainly are still rather ignorant as to the exact process of Abiogenesis, we are just as certain that it is the only scientific answer.
An interesting account at WIKI.....
https://en.wikipedia.org/wiki/Abiogenesis
starting with...."Origin of life" redirects here.
For non-scientific views on the origins of life, see Creation myth."
"Abiogenesis, or informally the origin of life, is the natural process by which lifehas arisen from non-living matter, such as simple organic compounds. While the details of this process are still unknown, the prevailing scientific hypothesis is that the transition from non-living to living entities was not a single event, but a gradual process of increasing complexity that involved molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes.[9][10][11] Although the occurrence of abiogenesis is uncontroversial among scientists, there is no single, generally accepted model for the origin of life, and this article presents several principles and hypotheses for how abiogenesis could have occurred".
And an interesting account here......
http://www.rationalskepticism.org/chemistry/calilasseia-78-papers-on-abiogenesis-t845.html
"Blind faith" in chemical evolution? Guess who hasn't read the scientific literature!
Here's 78 scientific papers from the abiogenesis literature, that demonstrate conclusively that "blind faith" doesn't apply.
Instead, what applies is direct experimental confirmation that the postulated chemical reactions WORK, and work under the prebiotic conditions postulated to have been present on the early Earth ...
List of 78 papers at link......
LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL
The best that can be said for any non scientific answer or religious/ID myth, is that the BB and our laws of physics including GR, say nothing about the time at t+10-43 seconds. In other words the BB tells us how the universe/spacetime [as we know them] evolved at that t+10-43 second point. But again as indicated, any answer is simply based on unsupported myth.
Scientifically speaking though, we do have reasonable scientific speculation at that time and it is pretty well summed up here.....
https://www.researchgate.net/publication/230969681_The_Universe_The_ultimate_free_lunch
Gee, my old mate /s are going to have some fun with that boo boo 
But, that might have a verifiable explanation that I'm too lazy to seek. lol 
