That welding was done before the rifles were loaned to the veterans' organizations. They were not meant to destroy the rifle, but to keep it from being made to fire live ammo without the alteration being obvious. The small tack welds I have seen, and that looks like one of them, should not create any danger. Of more import is the question of barrel condition, as most of those rifles were fired with corrosive primed blanks and couldn't be cleaned.
Anyone getting one through CMPshould make sure to retain the papers so there is no doubt about the legality. Some vets' organizations forgot that the rifles were loaners and sold them or gave them to members, not realizing that they thus became stolen goods.
Jim