OP request seems logical to me. If player A has a higher rating than player B and player B disconnects in an even position, player A has two options:
(The exact numbers depend on the rating difference, I choose arbitrary values to show the point)
* Claim victory --> +5
* Call a draw --> -1
So if +5 or -1 are both valid options, then I don't see any reason why +/-0 should be a problem for the rating system because zero is in between. However, I don't have a strong opinion on whether it's worth implementing this option, since -1 and 0 are almost the same anyway:)
(The exact numbers depend on the rating difference, I choose arbitrary values to show the point)
* Claim victory --> +5
* Call a draw --> -1
So if +5 or -1 are both valid options, then I don't see any reason why +/-0 should be a problem for the rating system because zero is in between. However, I don't have a strong opinion on whether it's worth implementing this option, since -1 and 0 are almost the same anyway:)