On ukwiki, we have a couple of long term abusers (LTAs) that among other things create a lot of accounts with abusive usernames or usernames that contain PII that under oversight policy should be suppressed.
The problem is that those accounts already have their talk page created by Extension:NewUserMessage's bot, and in order to completely suppress the abusive username one needs to delete the talk page as well as revdel the page creation and deletion log records an example: https://uk.wikipedia.org/w/index.php?title=Спеціальна:Вилучити_редагування&target=Спеціальна%3AЖурнали&type=logging&ids=18763279%2C18763260
This is at the very least annoying at worst a potential security issue (though I do not feel like this warrant a restricted ticket for this particular thing).
One way I propose to mitigate this is by creating a configuration parameter (to follow the extension's approach I guess it would be a ns8 page that any admin can tweak as necessary) to delay the welcome message by a specified amount of time (strtotime? time in seconds?) as well as make the extension ensure that neither a local block nor a global lock exists at the time of the welcome (potentially the latter can also be made a configurable thing, but I cannot think of a valid usecase where one would want to welcome banned users).
I guess there is a question of what to do if the block expires or is removed and/or if the lock is removed, but I my personal take is that in those situations it is not a problem if the user ends up not being welcomed.