They used to ban parents having any contact with children in hospitals, because the sadness and distress of the children after contact made them think a clean break was best. Then they did some actual research and discovered the damage if they didn't see them was immense.
That's not the same situation, not remotely - your kids are with loved, familiar people, and not unwell, nor dealing with scary procedures - but the (very limited) similarity is that your kids will be sad you aren't there, and the adult discomfort with seeing that is their issue to deal with. They are making it the children's. They may have the very best of intentions, but they are wrong. The children need to know you are somewhere, and that you love and miss them too, but will be home soon. And they would be best hearing it from you.
It won't affect your bond in the least, though. Please don't think that it might. They may be a bit clingy and they may be a bit challenging when you return, but that's all. And it will wear off.
It's hugely, hugely disrespectful of your husband to make a unilateral decision on whether you Skype with the children, most especially bringing his parents' opinions in as ballast. It is none of their business.
Were you sounding sad or anxious when talking with them at all, or were you upbeat? And does he often "punish" you, or ignore your feelings and opinions?