To the OP: I've been around a lot of Japanese arts (not as many as some on this board), including Aikido. I've never seen a red sash. I've never seen a sash (as a rank) at all, in any of them. A red belt would usually be a very high rank (above black, usually reserved for a very small number of very senior practitioners - unlikely to be achievable before age 40 or 50 in most cases). In a few, as others have said, it may show up as a lower rank. In some Korean arts, I think a red belt shows up just prior to black.
But no, unless he was in some odd offshoot I've never heard of, he was never a "red sash" in Aikido.
But no, unless he was in some odd offshoot I've never heard of, he was never a "red sash" in Aikido.