Steve, I'm not sure I follow you. Tape is a proper means of insulation, and it's certainly applied 'after' the splice is made. I don't have any problem with heat shrink tube as covering for a splice.
NEC is quite clear about soldered connections being electrically and mechanically secure *before* applying solder. This is impossible with tape or anything else applied *after* the solder connection is made.
If a simple twist suffices as the primary electrical and mechanical connection (is this in NEC anywhere? If so, then tape for insulation should be fine. But a twist is not sufficient for ground wires without a crimp ring or other listed device, so I don't see how it would be acceptable here, either.
