The seamstress who said that the tent had been cut from the inside, may have had a knowledge of fabric, but maybe not hunting knives and how they are used.
The tent could have been cut from the outside.
A hunter would not slash the tent, like he was wielding a machete, but would use a knife like he was skinning an animal, which involves inserting the point, then lifting up and away, with the edge upwards, which would give the impression that it was cut from the inside.