The ticket says "In some cases, some transactions with joinsplits do not get mined." So this does not prove droffels point. He said all tx with only z-addresses could not be mined.
He's 100% correct, as is the GitHub issue. Transactions that were z-addr -> t-addr, or vice versa, were being mined, but private transactions (my z-addr pays your z-addr) were not.
Any other source for this claim?