Jane,
Yes there is justification, especially since a recurrence is involved. If he had radiation the first time it may have negated the recurrence. If the cancer was in the same area then there was a spread involved for there to be a recurrence. Your first statement is in conflict.
The word recurrence implies that its from the original tumor site. A metastesis is where cells break off and set up a new tumor site elsewhere in the body and it is typically "distant". i.e., lungs, liver, etc.

Radiation's no walk in the park but many of us have survived it and are doing quite well today. I had the maximum amount and have very few side effects 2 years out from Tx.

Radiation is often given for prophylactic reasons. I would seek a few more professional opinions on this, preferably from a comprehensive cancer center, with a balanced perspective of the risks and benefits.

Ps I am 2 years younger myself