I would disagree with this one. It isn't anyone's fault other than the defense that there was no attempt to tag R2.

You did not say where the runners were when A) the ball was thrown to 2nd or B) when you yelled time. That matters, I think.

R1 had made it to third, R2 was between first and second.

Both had started to return to their dugouts when the out was called at second. I waited a few seconds before calling time.