It's not ideal but they do warn you (even on the tube) haveing water in a pc isn't ideal but there are ways to manage it, it's no different, just care and attention is required.
Surface of copper/nickle is fine, thin buildup over surface possable after many weeks - lap or use braso to full remove. Will hide etched spec on chip surface if unlapped.
Further reading has lead me to beleive that the removal (especially of lapped HS) is due to surface tension of the liquid metal on very flat surfaces. Twisting action is recomended removal technic.
Can reapply with LP without issue I'm told, but not used it myself so read up fully if you going use this stuff.