No to be mean but I noticed a few things
1. While the part Gambit destroyed is big the size should be found using Gambit's size and not assume sizes
Here is a pick for reference
I also made a quick size reference for showing that the found size is wrong.
In this pic I use Gambit's knee to heel height to find the size. Calculator for reference:
https://hpc.anatomy4sculptors.com/
Gambit's canon height is 6'1" which is 186 cm
Gambit's heel to knee height: 46.5 cm
46.5/76 = 0.6118421053 cm/pp
0.6118421053*1511 = 924.4934211 cm or 9.24 meters
2. Gambit didn't actually destroy the entire chunk. In the scene immediately after that we see a shot walking away and we see the chunk that fell.