Vilenkins verdict: All the evidence we have says that the universe had a beginning.
Considerations:
1) Vilenkin doesn't believe there is any "the universe" that could have a beginning
2) You link to an atheist blog (commendable) for balance regarding Craig's use of Vilenkin. However, we don't need any source but Craig to castigate and criticize Vilenkin:
You've read simplifications of stuff like Craig's work. It's told you that you can't reach any point by going back in time if time is eternal. You've even cited Craig's use of Vilenkin in Craig's popular works, despite the fact that in his technical work (including a review of Vilenkin's Many Worlds in One) Craig castigated Vilenkin for referring to "eternal inflation" and infinitely many universes, his dismissal of god or the need of any creator. Criag writes "Although Vilenkin observes that "Inflation is eternal in practically all models suggested so far...." in none of his popular articles does he ever suggest that Vilenkin posits anything more than an absolutely confirmed beginning of time.
3) When you can tell me
which universe Vilenkin believes "had a beginning" in accordance with his research (e.g., Garriga, J., & Vilenkin, A. (2008). Prediction and explanation in the multiverse.
Physical Review D, 77(4)), perhaps this might be more meaningful.
With the proof now in place
1) It isn't a proof. It involves proofs.
2) Can you provide the proofs that you refer? Obviously I wouldn't ask for anything prior to
Borde, A., Guth, A. H., & Vilenkin, A. (2003). Inflationary spacetimes are incomplete in past directions. Physical review letters, 90(15)
but it would be nice if you could demonstrate how boundaries work not in terms of "time' (which Vilenkin doesn't) but both spacetime and the origins of spacetime.
cosmologists can no longer hide behind the possibility of a past-eternal universe.
They can, however, determine that such a possibility isn't just impossible but is meaningless in multiple ways.
There is no escape: they have to face the problem of a cosmic beginning.
Which is a contradiction in terms.
Craig on Vilenkin on Cosmic Origins
Craig has a longer review of Vilenkin he writes for the non-specialist audience he can't lie to as easily in which he extensively criticizes Vilenkin and does so not for Vilenkin's actual research but for a popular science book simplified for the layperson. Craig uses Vilenkin when manipulating a poorly informed audience and abuses him when he attempts to address his peers.
In sum, I think you can see how misleading the physicists statements to you were
Alternatively, you could try actually reading physics literature rather than rely on quote-mined simplifications from interviews and similar methods in which scientists are asked questions and the simplest and most sensationalist of these are picked for inclusion in some popular science article. You may find a rather significant difference.
The prediction of the standard model that the universe began to exist remains today as secure as ever
You do realize that neither Borde, Guth nor Vilenkin support the standard model, correct?
"Inflationary models of cosmology yield a rather different picture of the full present Universe (as opposed to the part of it that we can directly observe) than that given by the standard big bang cosmology."
Borde, A., & Vilenkin, A. (1994). Eternal inflation and the initial singularity.
Physical Review Letters, 72(21)
The person who believes that the universe began to exist remains solidly and comfortably within mainstream science.
Guth, A. H. (2000). Inflation and eternal inflation.
Physics Reports, 333, 555-574.
I hope semantics will not be employed to try and claim Vilenkin did not mean exactly what he said.
How about using what Vilenkin wrote instead of quote-mined statements by Craig and similar dishonest sources (I have great respect for many an apologist, C. S. Lewis for reasons of fondness and an Einstein-like ability to render the simple into the meaningful, Kreeft for replacing him in some sense, Plantinga for his technical nuances, etc., but Craig is the Ehrman of apologists- saying one things to a mainstream audience while contradicting himself when writing to those he can't mislead).