The comment he replied to said nothing about Tesla competing with BMW on all models, the original comment was referring to model 3 vs bmw 3 series and C class Merc
His point was that the supply chain is there and working well. Tesla has a non-trivial amount of work to do to be able to catch up to those sorts of production numbers.
The fact is that BMW produced 40x more vehicles in 2015, which would suggest their supply chain and support network is much more robust.