The squad explored and moved onto the next node (advance 3) and thankfully found the security door beyond it still passable. It took the Demolition expert three turns to find a way through to the next node Demolition 2 - even with help from the Team leader). The node was again thankfully empty.
I'm fairly certain that demolition checks cannot be modified by any Leader command bonus. Check rule 4.4/"command" on page 5 regarding skills marked with asterisks.
IMO Demo checks seem to be one of the toughest in the game to get past. Wondering if a "demo charge" resource (Pull random chit, add to skill check) wouldn't be a good addition.