That is quite open for debate.
First of all, define "compromise" in this specific context. What exactly are you accusing +ABL of? Let's define our terms.
Your own hardline/sedevacantist stance has colored your view of the rather distant past -- 30 or 40 years is a good chunk of time, in terms of human lifespan.
Treating with the Pope, we're talking about the Vicar of Christ here, when no one had been betrayed yet, is not compromise. "Someone had to try". Afterwards, YES, you should know better. We have since sounded the depths of the Crisis in the past several decades, and now any person with their eyes open is blackpilled about the Modernists and the state of the Conciliar Church in Rome. Most sane men today think only God is going to be able to sort it out. But that was not the situation in 1983. The Crisis was still young!
Going back to see if any of your house is still there, in the days following a massive wildfire, isn't crazy.
Going back 40 years later, long after the wildfire burned the entire town and it's common knowledge -- THAT would be crazy.
+ABL did the former, Bp. Fellay did the latter. There is no comparison in the actions of the two men.
Action X done in 1983 might not be compromise, whereas the same action X done in 2012 would be the most craven and cowardly of compromises. It's all about the circuмstances.
Just like packing up the family and moving 1,000 miles could be the peak of wisdom and prudence for one family, but the height of folly for another family. The CIRcuмSTANCES define whether an action was prudent or foolish, and a wise action or a craven, foolish "compromise" with error/evil.
You are absolutely right, Matthew, except for 'it is open for debate'. There is no debate.
As you say - very, very different circuмstances. All those prelates at the Council with ABL, they didn't suddenly become non-Catholic after the Council. So also for all those true priests all over the world, trained, many of them, in solid seminaries. So too, many confused faithful still in the pews, wondering what had happened to their Church.
Archbishop Lefebvre suddenly being calumniated by Church and world and it was bruited abroad that this bishop was not Catholic. He had a duty to go to the Pope, to demand that the true religion be favoured by the hierarchy, to repair the grave scandal.
To simply declare, falsely, that the Pope was deposed or to ignore the plight of all these good clergy and faithful deceived by the revolution would have been to abandon so many souls. It would have looked like schism, and it would have been very close thereto.
This was the situation in 1978 when ABL was received by Paul VI who, in the words of the Archbishop, seemed ready to grant his request, until Cardinal Casaroli came into the room and warned the Pope vehemently against this bishop who was making a 'flag' of the old Mass.
At that time, the Archbishop had support from many bishops the world over, most of whom wanted to remain anonymous. One could only imagine what might have happened if Tradition were allowed again by the authorities.
The situation in 1988 still retained some of this character, yet much less so and that is why the Archbishop was reluctant to go to Rome before the consecrations, he did it very much to please those around him who requested it, and he said after the consecrations that the Society's truest friends feared what he was doing and warned him against it to the point where he said 'if anything, I went too far'. Wind the clock forward 25 years to 2012, the situation was entirely different and the Archbishop had long before warned his priests that it was a 'strict duty' to separate from this Conciliar Church until it returned to Tradition, that all their maneuvers that appeared to favor Tradition were simply traps.
Yes, in those early days, Archbishop Lefebvre requested the 'experiment of Tradition' in the hope that the hierarchy would see the good fruits vs the bad fruits of the reform, and return to the right path.
By 2012, that experiment had already taken place without the authorisation of Rome and in spite of that had borne extraordinary good fruit. Rome saw the good fruits. Did this have the effect that the Archbishop had hoped? Was Rome prepared to admit they were wrong and that their so-called reform was a mistake and that we must return to Tradition? Absolutely to the contrary. They continued to pursue an ever more perfect implementation of the Council! Even after Pope Francis had demolished the Franciscans of the Immaculate and forbidden their use of the Traditional liturgy, we still had Bishop Fellay saying 'this could not be a trap, this could only be friends wanting to do us good, wanting the spread of Tradition in the Church'.
Wake up you blind people who say that Bishop Fellay was only doing what Archbishop Lefebvre did. That is a contender for the lie of the century.