When is the last time the US military actually "defended" its own territory/country, heck even just its own continent? How does droning people in Pakistan, and having troops stationed in Syria "help" with "defending" the US?
Even worse: This kind of logic is then used by NATO allies to justify their own partaking in US foreign military adventures. That's how the Germans "protective military" ended up "Protecting freedom at the Hindukush" [0].
[0] https://www.afghanistan-analysts.org/protecting-freedom-at-t...
Almost invariably, to provide the american military with hardware is to arm an offensive force.
As for improving military training and tactical hardware, yes it will most likely be used for offensive purposes. The absence of the technology wouldn't stop those offensives though; the absence would just result in less-well-trained less-well-equipped troops in the same situation. As has been pointed out elsewhere, bad training and lack of information is likely to lead to more deaths.
While I think it's wonderful employees of major tech companies are trying to drive more ethical choices, this was an odd choice for a line in the sand.
That's a bold statement to make, particularly in the context of the US pulling out of INF and JCPA (Iran deal), especially when accounting for the reality that nuclear weapons "modernization" is still steadily going on [0]. That's not something you'd expect to see in the "post-nuclear era".
Particularly not with a US president who clearly does not understand nuclear weapons and would just love to sell and use them.
[0] https://thebulletin.org/2017/03/how-us-nuclear-force-moderni...
Also fear to be millitary contractor for your own country seems pathologic to me.
https://en.wikipedia.org/wiki/List_of_attacks_on_U.S._territ...