If you offer a mTIE you do it because you want an advantage for your team. Either you want to save your effort and play a TIE or you don't think your team can beat the other team on equal effort and will break the TIE. It's a power play. Only way to keep the power for your team is to either ignore the offer or take and break the offer. You can never fault a team for breaking a mTIE offered to them.