There's also a famous saying, though, that any prosecutor could get a grand jury to indict a ham sandwich (interestingly, I never knew the original author of that quote was a judge who subsequently served 13 months in prison, https://en.m.wikipedia.org/wiki/Sol_Wachtler).
But, the overall point is that the bar for grand jury indictment is intentionally low. I'm not going to speculate on aspects of the indictment because I don't know what they are yet (and it always amazes me how so many folks always dig in to be part of "their team" even before they know what the game is), but before the indictments I did see some legal experts who were definitely not Trump fans argue that it was not a case they would've brought.