During the Patriots-Broncos game on November 29, 2015, Brock Osweiler had his hand hit as he was passing the ball, causing it to pop up and end up in the direction of the linemen. Could an offensive lineman legally catch the ball? The ball was not touched by the person who hit the hand of the QB.
The key to what you’re asking is your statement:
The ball was not touched by the person who hit the hand of the QB
If you frame that in the context of the eligible receivers rule you'll see…
Article 5 Eligible Receivers.
The following players are eligible to catch a forward pass that is thrown from behind the line of scrimmage.
(a) Defensive players.
(b) Offensive players who are on either end of the line, provided they either have the numbers of eligible players (1-49 and 80-89) or have legally reported to play a position on the end of the line. See 5-1-2.
(c) Offensive players who are legally at least one yard behind the line at the snap, provided they either have the numbers of eligible players (1-49 and 80-89) or have legally reported to play a position in the backfield.
(d) All other offensive players after the ball has been touched by any defensive player or any eligible offensive player.
The key to your question is 5d. Since the defender did not touch the ball, the O-lineman is not eligible.