Back in those days, we were never allowed to question The Ballard and there seems to be lingering grudges towards folks who questioned Ballard early on. I guess perpetuated by the fact that more people have climbed on board the bus Moose started. Moose's reasons for his opinions have always made sense to me, and he has stated them frequently. Just questioning the Nelson pick set people off for some reason.
Your reason for the pick seems likely, however, there is also a belief that a GM should understand how Luck held the ball too long, in that simply adding overpriced olineman isn't really the way to fix the problem (when there were about 6 Gs available in the first round of that draft, and some thought Nelson might fall out of the top 10 given the needs of the teams). In fact, when Luck returned, he was given a new offense where he dinked and dunked the ball a lot...which goes unnoticed by many who want to attribute the oline's success solely based upon the new oline players. Then he started throwing long again as the season matured. It was Luck adjusting his style as much as the new players, IMO.
And it was more than protecting Luck, many liked the pick because Nelson was going to be a perpetual pancaker in the NFL, which supported the idea he was worth the high investment. No, that never was gonna happen.