Honestly, I hate SW exactly because of its tricky approach, it looks to me kinda cobbling things in a hacker way. I love hack but not when it comes to core algorithm, as a rule of thumb we should keep core components elegant and smart.
You do know that many innovations in Bitcoin were rolled out this way, right? P2SH is treated by non-P2SH-aware nodes just as a hash preimage lock. OP_CHECKLOCKTIMEVERIFY and OP_CHECKSEQUENCEVERIFY for non-aware nodes are just no-ops.