He never said that we will only be signing young and British players in future. Pearson has stated that we already have 6 players signed up for next season, and that we've mainly been looking at players that are young and British for these signings.
He also said that we're still looking to add a halfback and another prop. These were stated separately to the 6 players already signed who are mainly young and British. Presumably, if we were to sign Chase he would be the halfback mentioned here, as the other 6 are already said to have signed.
In recent months, Hull have signed both Jay Pitts and Liam Watts (England Knights), as well as announcing the signing of Joe Arundel (England Knights). It has also been widely reported and rumoured that we have also signed Jason Crookes, although this has not been confirmed by the club yet.