Tilt that on its head and you could argue taking a winger off for a striker is a statement of intent in itself. If this argument that Bunn was "settling for a point" had any merit, surely he'd have been making defensive-minded subsitutions?
Surridge got 30 minutes, having been out injured for several weeks, and with another difficult game on Tuesday. Given his injury record this season, it seems quite sensible to me to ease him back in gently.