As Casper stated, hitting on the 1pt gains time to pick up a second checker, however unlikely that may seem.
Another factor that is often overlooked (and one that frequently works in the opposite direction) is that if Blue fails to pick up a second checker, his closeout position will be stronger if one or more of White's 2pt checkers get nudged forward to the 1pt. The gain is a combination of White missing in the bearoff, and blotting after (or especially if at the moment of) the closeout.
There is a tradeoff, in that if Blue hits now, White's first ace (unless the roll is 21) will result in Blue failing to get White's first 2/1 that he would have otherwise procured. However, the net gain in recycling rates to cause more 2/1's on average.
This is just the XG++ evaluation level, but compare the formations below when Blue's three closeout spares are 654, 653, 664, 663, 643, 652, 651, 543, 542, 541, 554 and 544, respectively. (The first line designates the closeout without White having moved any checkers 2/1.)
...3 on 2pt, 4 on 1pt = .365, .363, .313, .301, .297, .296, .290, .262, .246, .229, .233, .222
...2 on 2pt, 5 on 1pt = .377, .366, .317, .310, .293, .303, .288, .250, .237, .229, .228, .228
...1 on 2pt, 6 on 1pt = .447, .434, .389, .384, .381, .380, .367, .276, .320, .313, .311, .311
...0 on 2pt, 7 on 1pt = .380, .376, .322, .322, .318, .311, .302, .255, .257, .242, .228, .228
For the third line, the equity will sometimes be even higher because Blue will have gotten in a double. This happens when he is shooting at the second checker from the bar, misses, hits in front of the prime (sometimes White hits back and Blue misses the 23pt shot again), and closes out before White can get in her final 2/1.
A downside hitting on the 1pt immediately (double blotting) is that when White hits on the 23pt, it will occasionally cause problems for Blue because his checker on the 1pt doesn't get back "into play," Blue rolls awkwardly, has to leave a gap, and White slimes through to win a gammon.
Another downside is when Blue hits the second checker White might anchor on a higher point than she would otherwise. Thus, the gains of going after a second checker in this non-point-sequential fashion are a bit ameliorated.
That stated, the gains are probably net positive even when comparing to a stronger alternative than your exact position offered. In my expansive variant (see below), Blue's spare is moved from 4pt to 6pt, and the roll is changed from 63 to 65. In this way, the original two plays are represented (by transposition), while a more competitive candidate play is introduced.
I ran two XGR++ rollouts. The first one (below) is at your –7–7 score with centered cube. The second rollout is for money, with the cube in the more typical location (see below).
The preference of hitting on the 1pt immediately (triple blotting) is likely overstated even in high level rollouts. For pure containment positions, I'm reluctant to draw meaningful conclusions based on rollouts, because I don't know enough to what extent various bots botch the checker play and/or cube action. For example, if a bot might follow up by hitting on or making the ace point anyway when it shouldn't, then hitting on the ace point immediately will perform better than it should.
Therefore, I caution you not to believe containment rollout results blindly, though Blue's prime is far enough advanced that most of the bot-botching is probably squeezed out of this position.
Nack
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| XGID=-aAABBCBBB-------------cd-:0:0:1:65:0:0:0:7:10 | |||||
ATS, Cube centered | |||||
| 1. | Rollout1 | 9/3 6/1* | eq: +0.302 | |||
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| 2. | Rollout1 | 8/3 8/2 | eq: +0.276 (-0.026) | |||
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| 3. | Rollout1 | 9/4 9/3 | eq: +0.242 (-0.060) | |||
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| 1 5184 Games rolled with Variance Reduction. Dice Seed: 36223632 Moves and cube decisions: XG Roller++ | ||||||
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| XGID=-aAABBCBBB-------------cd-:1:1:1:65:0:0:3:0:10 | |||||
Money, Blue owns cube | |||||
| 1. | Rollout1 | 9/3 6/1* | eq: +0.394 | |||
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| 2. | Rollout1 | 8/3 8/2 | eq: +0.375 (-0.020) | |||
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| 3. | Rollout1 | 9/4 9/3 | eq: +0.345 (-0.049) | |||
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| 1 5184 Games rolled with Variance Reduction. Dice Seed: 77188236 Moves and cube decisions: XG Roller++ | ||||||