You can read her "contract" details here - https://www.dashwhale.org/p/dash-youtube-show - I dont think it makes her exclusuve to Dash, but conflicts of interest will most likely be frowned upon by masternode voting party.
She wrote this recently.
http://dashpaymagazine.com/index.php/2016/06/01/top-crypto-best-infrastructure-investment-ratio/
I'd hope the dash community would take the broad view on Amanda's participation in the wider crypto space. The more she's seen as a respected sage and advocate for crypto generally the better it reflects on them (given she's nailed her colours to their mast, so to speak).
I can speak for myself in that i wouldnt mind her doing work for other projects. Shes a great spokesperson for the industry as a whole.