The USPS allegation was 100% untrue as reported by the postmaster general (who you think would be someone Trump would have consulted).
The tax stuff is really none of his damn business (because it is really a state tax code issue at this point, not a federal issue)
If Trump does anything to attack Apple, it will be because he things doing so will benefit the US economy (likely because someone else told him it would). Things like convincing Apple to make certain parts in the US, even if doing so would increase prices in the US (and dramatically do so elsewhere in the world).