think about it, it's a cubic meter of solid steel, it probably could withstand explosions

if you might ask all the other modmakers out there too that use steel in their mods and all of them agree, this might be possible :D

Mindforger kinda nailed it. There are a lot of mods that add steel blocks, having a drastic difference in behavior in those would be a bit odd.

That said, IE already has "Leaded Concrete" which features increased resistance. I don't believe it's as strong as obsidian, but it still withstands explosions, afaik.