OOC: Should point out that at the point where Alastair invaded Galen's mind, Galen responded with the mental equivalent of Force lightning. Though nothing visible would happen, that would be very painful and startling to Alastair.
Actually, I imagine that Reginald doing the same would cause a negative effect on Alastair as well. Different, but still bad. Just like he described it, in fact. So, you know, react accordingly.