There are circumstances where a Visitor visa could work and it be OK, for examply if LG whgo got a mention were supplying machinery and they sent over installation crew, however it seems they went well beyond this.
And by the sound of it pure illegals, overstayers and who knows what.
Many moons ago my Brother worked for one of the Big 4 and was seconded to NY for a few month, I always assumed he went on a L but nope VWP.
I remeber him mentioning that there were loads of IT guys visiting from India, packed into a house, seems they applied en masse and the ones that got one were sent over for 6 months.