It’s not God that’s capricious. It’s not God that does the rebelling.
It is man.
Your theology has you being omniscient about your future life, decisions and final judgement.
And therefore it makes no sense if I propose you might be wrong.
Not God, you.
If a believer cannot commit the unpardonable sin, then I have nothing to worry about.
The only way someone can commit that sin is as an unbeliever and at that point there was no forgiveness to lose in the first place because they never had it in the first place.