But as is likely the Spurs board have said they don't give a **** about the league or fa cup, they are only interested in the league/champions league. Therefore it will be acceptable to them to experiment with a reserve team.
At Oxford Clotet was appointed on the basis of buying in to a development plan, trusted with a budget which he blew on some questionable quality players, and told to compete for promotion. Losing 0-7 at home to a side in the same division would likely be a major black mark, even if it wasn't the one that pushed him out of the door.