We’re creating not just one but three problems for ourselves by not giving Henderson an extended run sooner rather than later.
1) We are dropping points due to DDG
2) It takes any GK time to bed in and get settled, so if we don’t give Henderson a run now, whilst the team is still a work in progress generally, we’re just increasing the pressure on him to perform when he’s thrown in and it might really matter.
3) It’s obvious to every man and his dog that De Gea is finished. So what we now need to do is workout who plays in goal next season. If Henderson is poor between now and the end of this season, we know we desperately need a GK, even if its a stop-gap. If we wait until next season to try Henderson properly, we might have another season with a sub-standard GK.
Basically, I can’t think of any logical reason now not to play Henderson until the end of the season.