Not sure where you get that they're ignoring it. TFA says nothing of taxes, and that burden falls on the buyer anyway. Unless you're saying that the IRS's guidelines mean it can't be used to buy things for some reason, which is just not true at all.
Ignoring in the sense that Paypal thinks its worth their time to facilitate consumer transactions based on bitcoin.
As the bloomberg article states, if I have to factor in my my capital gains tax liability with each purchase of an ebook or mp3, then that is a royal pain and would lessen my desire to use bitcoin for everyday purchases.
It seems to me that perhaps Paypal just see's the IRS guidelines as a non-factor for consumers who will largely just ignore the guidance similar to how consumers are technically supposed to pay state sales tax on online purchases.
