Tesla installed 29 MW of solar last quarter, compared to a peak of 253 MW at Solar City before the acquisition. First Solar, which isn't an apples to apples competitor since it specializes in utility scale, is on track to produce 1375 MW per quarter of panels this year.
Tesla's solar business is dead. They might turn it around with the solar roof product, but if that succeeds it will make Tesla Energy even less of a competitor to First Solar, since it has zero relevance to utility scale solar.
Even if Walmart had evil intent, why give Solar City the PR boost of hundreds of installations in the hope that they'll fail and they can later sue?
It's easy to make a nice conspiratorial quip, but there's nothing of substance here. Jumping at every shadow just numbs you for when you really should be angry.