The Chain of Almost Locked Sets (ALSs):
(a) box 2: D2 and F2 (b) row 9: C9, D9, F9 and G9 (c) col H: H1, H7 and H9 (d) col I: I1, I2, I3, I6, I7 and I8share the Restricted Common Candidates (RCCs) such that they "push" each other along the chain resulting in the z value (7) being in either the first or the last ALS, hence 7 can be eliminated from any cell/s which see all 7's in both the first and last ALSs.
Therefore 7 can be removed from G2.
The logic of an ALS-XY-Chain is a bit complex. Each pair of ALSs in the chain (A and B, B and C, and so on) share a common restricted candidate, and if an Almost Locked Set, by definition, looses just one of it's values then it becomes a Locked Set, so that when we chain ALSs using there common RC's we know that each RC will be in this ALS or that ALS; which means that one of the other values in "the recieving ALS" is "pushed" into the next ALS in the chain, and so on around the chain; so they all fall-down like dominoes IN EITHER DIRECTION; so with a "loop" of ALSs that meet back at the first and last ALS, we can remove all values common to the first and last ALS from any cells outside of both ALSs which see all occurrences of that value in both ALSs. Simples! Not!