possibly 6.25 since according to what @kano said in previous page the miners may be worried that the block they find (which would give them 6.25 bitcoin reward + whatever fee) could become invalid and rejected by the rest of the network!!
Maybe the offer could become more appealing after a couple halvings. OP could also try raising the issue on github, hopefully Bitcoin Core could be updated to remedy this problem.
i seriously doubt anything about bitcoin core is going to change unless there is an overwhelming number of similar cases that have lost their coins to this type of non-standard scripts.
although i think the change itself is very easy (possibly it needs changing one line of code), the addition of an option to let the user enable/disable through command line may not be.