WEB Gal 1:6 I marvel that you are so quickly deserting him who called you in the grace of Christ to a different “good news”; 7 and there isn’t another “good news.” Only there are some who trouble you, and want to pervert the Good News of Christ. 8 But even though we, or an angel from heaven, should preach to you any “good news” other than that which we preached to you, let him be cursed. 9 As we have said before, so I now say again: if any man preaches to you any “good news” other than that which you received, let him be cursed.
This phrase, "other gospel", has been used by some as evidence that "we cannot assume the approval for something when none is given". But in using it thus, the passage is made to say something it doesn't say.
The "other gospel" which that passage warns about is a "gospel" that requires the Gentiles to keep the Jewish law of Moses. You can't just pull those few verses out of context; if you read them in context, you should be able to see that the "other gospel" of which they speak is summarized at the end of the next chapter, and the beginning of the one after that:
WEB Gal 2:21 I don’t make void the grace of God. For if righteousness is through the law, then Christ died for nothing! 3:1 Foolish Galatians, who has bewitched you not to obey the truth, before whose eyes Jesus Christ was openly portrayed among you as crucified? 2 I just want to learn this from you. Did you receive the Spirit by the works of the law, or by hearing of faith? 3 Are you so foolish? Having begun in the Spirit, are you now completed in the flesh?
The entire book of Galatians is dedicated to the theme that we are justified by faith, not by keeping this regulation or that rule or some legal system like the law of Moses (he also speaks of this in other places in his writing, such as in Col 2:16ff, where he says that Christianity is not about rules and regulations like "don't touch, taste, handle", or such as in Rom 14 where he says that the kingdom of God is not about rules such as eating or not eating, drinking or not drinking, keeping a holy day or not keeping it, but rather is about joy and peace and "doing the right thing" throughout your life's walk).
This false teaching which Paul is combating throughout the book, that Gentiles must keep the law of Moses (as we see the Jewish Christians teaching in Acts 15:1,5), is what he's referring to when he mentions "another gospel". He is not referring to the idea that "we cannot assume the approval for something when none is given". In fact, this claim is the very thing Paul is arguing against, saying:
WEB Gal 5:1 Stand firm therefore in the liberty by which Christ has made us free, and don’t be entangled again with a yoke of bondage. ... 4 You are alienated from Christ, you who desire to be justified by the law. You have fallen away from grace. 5 For we, through the Spirit, by faith wait for the hope of righteousness. 6 For in Christ Jesus neither circumcision amounts to anything, nor uncircumcision, but faith working through love.
He says that if you want to be a law-keeper, you have to score 100% on your law-keeping, or you fail completely; none of us can score 100%; that's why law-keeping can't save us. There is NO law that will save us, not even the law of not assuming we have approval for something when none is given. (If there were ANY law that could save us, it would have been the law of Moses - Gal 3:21 "For if there had been a law given which could make alive, most certainly righteousness would have been of the law" - but it couldn't do it.) This is Paul's point in Galatians, and in much of the remainder of his writings, that we are not saved by keeping rules, such as "you must have authorization to breathe" - that's not a very freeing gospel; it's just as binding as the old covenant was, just with different rules.
Regardless of whether you can accept this teaching, that Paul is preaching against meticulous rule-keeping as a means of salvation, the use of Gal 1:6-9's "other gospel" to mean we need authorization for what we do is to simply take that passage out of context and use it to say something it doesn't say.