Ange won't ever compromise on his attacking values, regardless of the situation or opponent. Celtic copped a few hidings in the ECL last year, granted he didn't have the cattle, but they continued to play the same every minute of every game.
Sure he could have instructed the team to park the bus, and very unlikely come away with a draw, but perhaps at the expense of compromising on values which sends his players mixed signals and undermines the system that got them to 1st in the league in the first place. Think about next game, Spurs would have to pivot from a defensive mindset that was successful to an attacking one, and perhaps if they go a man down again or go a goal up there is an itch to adopt a defensive formation to protect the points they have, rather than chasing the three that are on offer like they did at Luton.
For Ange the most important thing is conditioning the players to stick to their attacking principles, even if it means occasionally throwing away points.