This is certainly possible, but I cannot imagine why blockchain.info would accept the TX on their node (which would have had to have happened if it is displayed on their block explorer) if the TX is outright invalid.
Good point. Not only would one expect blockchain.info to do all the basic checks but it had checked all of the input and output scripts and found no problem. Quite likely the transaction was just non-standard and I both failed to find the root problem and goofed in using various push_tx tools.
